Intelligent circuit breakers with visual indicators to provide operational status

ABSTRACT

A circuit breaker includes a circuit breaker housing, an air-gap switch disposed within the housing, and a first visual indicator configured to provide an indication of an open state and a closed state of the air-gap switch. The first visual indicator includes a first window that is formed as part of the circuit breaker housing, and first and second indicator elements disposed within the circuit breaker housing. The first indicator element is configured to move into position behind the first window as the air-gap switch is placed into the open state and thereby provide a visual indication of the open state of the air-gap switch. The second indicator element is configured to move into position behind the first window as the air-gap switch is placed into the closed state and thereby provide a visual indication of the closed state of the air-gap switch.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application62/849,847 filed on May 18, 2019, which is fully incorporated herein byreference.

TECHNICAL FIELD

This disclosure relates generally to power control systems and devicesand, in particular, to circuit breaker devices and systems forprotecting branch circuits from damage due to fault conditions.

BACKGROUND

Electrical circuit breakers are essential components in electricaldistribution systems. In general, circuit breakers are disposed in apower distribution panel (e.g., circuit breaker panel) which divides ahigh-current power supply feed of a utility power supply system into aplurality of downstream branch circuits within a given building or homestructure. Each circuit breaker is connected between the incominghigh-current power supply feed and a corresponding one of the branchcircuits to protect the branch circuit conductors and electrical loadson the branch circuit from being exposed to over-current conditions.There are several types of over-current conditions including overloadconditions and fault conditions. An overload condition is defined asoperation of equipment in excess of its normal, full-load rating, or abranch circuit in excess of its ampacity which, when the overloadpersists for a sufficient period of time, would cause damage ordangerous over-heating. Fault conditions comprise unintended oraccidental load conditions that typically produce much higherover-current conditions than do overloads, depending on the impedance ofthe fault. A fault producing the maximum over-current condition isreferred to as a short-circuit or a “bolted fault.”

Conventional circuit breakers are electromechanical in nature and haveelectrical contacts that are physically separated by either manualintervention of an operator lever or automatically upon the occurrenceof a fault condition or prolonged over-current condition, in which casesthe circuit breaker is deemed to be “tripped.” The separation of theelectrical contacts of a circuit breaker can be performedelectromagnetically or electromechanically, or by combination of both.

A significant problem with conventional circuit breakers is that theyare slow to react to fault conditions due to their electromechanicalconstruction. Conventional circuit breakers typically require at leastseveral milliseconds to isolate a fault condition. The slow reactiontime is undesirable since it raises the risk of hazardous fire, damageto electrical equipment, and arc-flashes, which can occur at theshort-circuit location when a bolted fault is not isolated quicklyenough. An arc-flash is an electrical explosion of the electricalconductors that create the short-circuit condition. The energy releasein an arc-flash can produce temperatures exceeding 35,000° F. at theterminals, resulting in rapidly vaporizing metal conductors, blastingmolten metal, as well as expanding plasma that is ejected outwards withextreme force. Therefore, arc-flashes are extremely hazardous to life,property and electrical equipment, particularly in industrial andresidential environments where the risk of a gas leak is significant.

In addition to being slow at isolating faults, conventional circuitbreakers exhibit large variations in both the time to trip and thecurrent trip limit in response to a fault or prolonged over-currentconditions. This variation is predominately due to the limitations ofthe electromechanical design of the circuit breaker device and theinfluence of physical factors such as mounting stresses and temperaturevariation. The variations in the time to trip and the current trip limitcan themselves vary from device to device even when the devices are ofthe same type, have the same rating, and are from the same manufacturer.

Conventional circuit breakers provide high isolation capability oncethey have been tripped. However, their slow reaction times, lack ofprecision and high degree of variability are all very undesirablecharacteristics. Not only do the slow reaction times result ininadequate protection against the possibilities of arc-flashes, but thehigh degree of variability and lack of precision make coordinationbetween multiple circuit breakers in a complex system almost impossible.

As a protection device, circuit breakers must be able to isolate a faultfrom the utility supply circuit even when the fault current greatlyexceeds the circuit breaker trip current rating and, thereby, protectagainst being an internal single point of failure. The AmpereInterrupting Capacity (AIC) rating of a circuit breaker indicates themaximum fault current (in amperes) that the circuit breaker device willsafely clear when a fault is applied at the load side of the circuitbreaker device. The AIC rating of a circuit breaker device denotes themaximum fault current that can be interrupted by the circuit breakerdevice without failure of the circuit breaker device. The AIC ratingdemands an extremely high level of short-circuit protection and domesticcircuit breakers are often rated at an AIC of 10,000 amperes or more.

Conventional circuit breakers do not implement functionality based onsmart decision making for breaking or isolating utility power from aload, or otherwise monitoring or measuring power components such asvoltage and/or current, and making intelligent decisions based onmeasurements and computations of the voltage and/or current. Incontrast, conventional circuit breakers operate to protect againstexcessive load power demand (e.g., current overload, short-circuits)based on electromechanical components in which circuit breakers aretripped by magnetic forces or mechanical forces that are generated byexpansion of a bi-metal element having metals with disparate thermalexpansion parameters. The lack of intelligent tripping operations andthe dependency on the brutal forces created in power distributionenvironment can result in excessive power conditions such as excessivearcing, slow trip response times, and dangerously high internaloperational temperature. The dependency of conventional circuit breakerson mechanical components to effect tripping, such as hooks, springsetc., increases the potential for disasters with regard to fire hazards,device unreliability, and potential loss of human life and property. Itis known that a common cause of electrical fires within a home orbuilding is the result of unreliable and faulty electromechanicalprotection devices and circuit breakers. Accordingly, there is a desireand need in the circuit breaker and protection device industry toeliminate the use of conventional electromechanical/thermomagneticcircuit breaker/protection devices and implement a more reliable andefficient solution for protection devices.

SUMMARY

Embodiments of the disclosure include intelligent circuit breakers andsystems and methods for implementing intelligent circuit breakers. Forexample, one embodiment includes a circuit breaker which comprises acircuit breaker housing, an air-gap switch disposed within the circuitbreaker housing, and a first visual indicator configured to provide anindication of an open state and a closed state of the air-gap switch.The first visual indicator comprises (i) a first window that is formedas part of the circuit breaker housing, (ii) a first indicator elementdisposed within the circuit breaker housing, and (iii) a secondindicator element disposed within the circuit breaker housing. The firstindicator element is configured to move into position behind the firstwindow as the air-gap switch is placed into the open state, such thatthe first indicator element is viewable through the first window toprovide an indication of the open state of the air-gap switch. Thesecond indicator element is configured to move into position behind thefirst window as the air-gap switch is placed into the closed state, suchthat the second indicator element is viewable through the first windowto provide an indication of the closed state of the air-gap switch.

Another embodiment includes a circuit breaker which comprises a circuitbreaker housing, an air-gap switch disposed within the circuit breakerhousing, an actuator mechanism disposed within the circuit breakerhousing, and a first visual indicator configured to provide anindication of a state of the air-gap switch. The air-gap switchcomprises a first contact and a second contact disposed in an electricalpath between a line input terminal and a load output terminal of thecircuit breaker. The air-gap switch is coupled to the actuatormechanism, and the actuator mechanism is operatively configured to (i)mechanically force the first and second contacts apart to place theair-gap switch into an open state and create an air-gap in theelectrical path, and (ii) mechanically force the first and secondcontacts together to place the air-gap switch into a closed state. Thefirst visual indicator comprises (i) a first window that is formed aspart of the circuit breaker housing, (ii) a first indicator elementcoupled to the actuator mechanism and (iii) a second indicator elementcoupled to the actuator mechanism. The actuator mechanism is configuredto move the first indicator element into position behind the firstwindow as the actuator mechanism places the air-gap switch into the openstate, such that the first indicator element is viewable through thefirst window to provide an indication of the open state of the air-gapswitch. The actuator mechanism is configured to move the secondindicator element into position behind the first window as the actuatormechanism places the air-gap switch into the closed state, such that thesecond indicator element is viewable through the first window to providean indication of the closed state of the air-gap switch.

Another embodiment includes a circuit breaker which comprises asolid-state switch, an air-gap switch, an actuator mechanism, a manualcontrol switch, an electromechanical actuator, control circuitry, and asensor switch. The solid-state switch and air-gap switch are connectedin series in an electrical path between a line input terminal and a loadoutput terminal of the circuit breaker. The air-gap switch comprises afirst contact and a second contact. The actuator mechanism isoperatively configured to (i) mechanically force the first and secondcontacts apart to place the air-gap switch into an open state and createan air-gap in the electrical path, and (ii) mechanically force the firstand second contacts together to place the air-gap switch into a closedstate. The manual control switch is operatively coupled to the actuatormechanism, and is configured to toggle between a first position and asecond position, wherein toggling the manual control switch into thefirst position causes the actuator mechanism to place the air-gap switchinto the open state. The electromechanical actuator is operativelycoupled to the actuator mechanism, wherein actuation of theelectromechanical actuator causes the actuator mechanism to place theair-gap switch into the open state. The control circuitry is configuredto control operation of the solid-state switch and the electromechanicalactuator, wherein the control circuitry is configured to generate (i) afirst control signal that is configured to place the solid-state switchinto one of a switched-on state and a switched-off state and (ii) asecond control signal that is configured to control actuation of theelectromechanical actuator. The sensor switch is operatively coupled tothe manual control switch and electrically connected to the controlcircuitry, wherein the sensor switch is configured to (i) detect atoggling of the manual control switch from the second position to thefirst position which causes the actuator mechanism to place the air-gapswitch into the open state and (ii) in response to detecting thetoggling of the manual control switch from the second position to thefirst position, output a third control signal to the control circuitry.In response to the third control signal, the control circuitry isconfigured to generate the first control signal to place the solid-stateswitch into the switched-off state before the air-gap switch is placedinto the open state to create the air-gap in the electrical path.

Other embodiments will be described in the following detaileddescription of embodiments, which is to be read in conjunction with theaccompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic circuit diagram of a conventionalthermal-magnetic circuit breaker.

FIG. 1B is a perspective view of a housing of the conventional circuitbreaker of FIG. 1A.

FIG. 2A is a schematic block diagram of an intelligent circuit breakercomprising an electromechanical switch, according to an embodiment ofthe disclosure.

FIG. 2B is a schematic block diagram of an intelligent circuit breakercomprising an electromechanical switch, according to another embodimentof the disclosure.

FIG. 3A is a schematic block diagram of an intelligent circuit breakercomprising a solid-state bidirectional switch, according to anembodiment of the disclosure.

FIG. 3B is a schematic block diagram of an intelligent circuit breakercomprising a solid-state bidirectional switch, according to anotherembodiment of the disclosure.

FIG. 4A is a schematic block diagram of an alternating current-to-directcurrent (AC-to-DC) converter circuit which can implemented in anintelligent circuit breaker, according to an embodiment of thedisclosure.

FIG. 4B is a schematic circuit diagram of the AC-to-DC converter circuitof FIG. 4A, according to an embodiment of the disclosure.

FIG. 5 is a schematic circuit diagram of an AC-to-DC circuit which canbe implemented in an intelligent circuit breaker, according to anotherembodiment of the disclosure.

FIG. 6A is a schematic circuit diagram of a solid-state bidirectionalswitch that can be implemented in an intelligent circuit breaker,according to an embodiment of the disclosure.

FIG. 6B illustrates active elements of the solid-state bidirectionalswitch of FIG. 6A during a positive half cycle of an AC mains supplyvoltage applied to the solid-state bidirectional switch.

FIG. 6C is a schematic circuit diagram of a solid-state bidirectionalswitch that can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure.

FIG. 6D is a schematic circuit diagram of a solid-state bidirectionalswitch that can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure.

FIG. 6E is a schematic circuit diagram of a solid-state bidirectionalswitch that can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure.

FIG. 6F is a schematic circuit diagram of a solid-state bidirectionalswitch that can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure.

FIG. 6G is a schematic circuit diagram of a solid-state bidirectionalswitch that can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure.

FIG. 6H is a schematic circuit diagram of a solid-state bidirectionalswitch that can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure.

FIGS. 7A and 7B schematically illustrate switch control circuitry forcontrolling a solid-state bidirectional switch, according to anembodiment of the disclosure, wherein:

FIG. 7A is a schematic block diagram of control circuitry that can beimplemented in an intelligent circuit breaker for controlling asolid-state bidirectional switch, according to embodiment of thedisclosure; and

FIG. 7B is a schematic circuit diagram of the control circuitry of FIG.7A, according to embodiment of the disclosure.

FIG. 8A is a high-level schematic illustration of an intelligent circuitbreaker according to another embodiment of the disclosure.

FIG. 8B is a high-level schematic illustration of an intelligent circuitbreaker which comprises isolation circuitry that is configured togalvanically isolate the intelligent circuit breaker from a load,according to an embodiment of the disclosure.

FIGS. 9A, 9B and 9C schematically illustrate an integrated currentsensor and energy metering circuit that can be implemented in anintelligent circuit breaker, according to an embodiment of thedisclosure, wherein:

FIG. 9A is a schematic diagram of a power supply block and a currentsensor block of the current sensor and energy metering circuit;

FIG. 9B is a schematic diagram of an over-current detection block of thecurrent sensor and energy metering circuit; and

FIG. 9C is a schematic diagram of an energy metering block of thecurrent sensor and energy metering circuit.

FIG. 10 is a flow diagram of a method for controlling switches of anintelligent circuit breaker in response to detection of faultconditions, according to an embodiment of the disclosure.

FIG. 11 is a state diagram that illustrates a control process which isimplemented by an intelligent circuit breaker to detect and protectagainst fault conditions, according to an embodiment of the disclosure.

FIG. 12 schematically illustrates an intelligent power distribution andmonitoring system which utilizes intelligent circuit breakers accordingto an embodiment of the disclosure.

FIG. 13 is an exploded view of a housing structure which can be utilizedto house switches and intelligent circuitry of an intelligent circuitbreaker, according to an embodiment of the disclosure.

FIG. 14 is a flow diagram of a process which is implemented by anintelligent circuit breaker to monitor energy usage on a branch circuitand protect against fault conditions on the branch circuit, according toan embodiment of the disclosure.

FIG. 15 is a flow diagram of a process which is implemented by anintelligent circuit breaker to monitor energy usage on a branch circuitand protect against fault conditions on the branch circuit, according toan embodiment of the disclosure.

FIG. 16 is a schematic block diagram of an intelligent circuit breakerwhich is configured to identify a type of load connected to the circuitbreaker and to control the load on the basis of the identified loadtype, according to an embodiment of the disclosure.

FIG. 17 is a flow diagram of a method of a load identifying and controlprocess which is implemented by an intelligent circuit breaker,according to an embodiment of the disclosure.

FIG. 18A is a schematic block diagram of an intelligent circuit breakerwhich is configured to monitor for ground-fault and arc-fault conditionsand provide circuit interruption in response to detected faultconditions, according to an embodiment of the disclosure.

FIG. 18B is a schematic circuit diagram of the intelligent circuitbreaker of FIG. 18A, according to an embodiment of the disclosure.

FIG. 19 is a schematic block diagram of a fault detection processorwhich can be implemented in the intelligent circuit breaker of FIG. 18B,according to an embodiment of the disclosure.

FIG. 20 schematically illustrates a current zero-crossing detectorcircuit according to an embodiment of the disclosure.

FIGS. 21A and 21B depict various waveforms that illustrate operatingmodes of the current zero-crossing detection circuit of FIG. 20,according to an embodiment of the disclosure, wherein:

FIG. 21A depicts waveforms that illustrate a mode of operation of theedge detection stage of FIG. 20; and

FIG. 21B illustrates simulated signal waveforms that illustrate anoperating mode of the current zero-crossing detection circuit of FIG.20, according to an embodiment of the disclosure.

FIG. 22 schematically illustrates a short-circuit detection circuitaccording to an embodiment of the disclosure.

FIG. 23 illustrates simulated signal waveforms that illustrate a mode ofoperation of the short-circuit detection circuit of FIG. 22, accordingto an embodiment of the disclosure.

FIG. 24 schematically illustrates an intelligent circuit breakeraccording to another embodiment of the disclosure.

FIG. 25A illustrates a power supply voltage waveform that is input to aline side of the intelligent circuit breaker of FIG. 24.

FIG. 25B illustrates an output voltage waveform on a load side of theintelligent circuit breaker of FIG. 24, when a solid-state switch of theintelligent circuit breaker is in a switched-off state and an air-gapelectromagnetic switch of the intelligent circuit breaker is in aswitched-closed state.

FIG. 26 is a flow diagram of a switch control process which isimplemented by a switch controller of the intelligent circuit breaker ofFIG. 24, according to an embodiment of the disclosure.

FIG. 27 schematically illustrates an intelligent circuit breakeraccording to another embodiment of the disclosure.

FIGS. 28A, 28B, 28C, 28D and 28E are perspective and schematic views ofan intelligent circuit breaker which comprises multiple visual indictorsthat are configured to indicate operational states of the intelligentcircuit breaker, according to another embodiment of the disclosure.

FIG. 29 schematically illustrates an intelligent circuit breakeraccording to another embodiment of the disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Embodiments of the disclosure will now be described in further detailwith regard to intelligent circuit breakers and systems and methods forimplementing intelligent circuit breakers. It is to be understood thatsame or similar reference numbers are used throughout the drawings todenote the same or similar features, elements, or structures, and thus,a detailed explanation of the same or similar features, elements, orstructures will not be repeated for each of the drawings. In addition,the terms “about” or “substantially” as used herein with regard topercentages, ranges, etc., are meant to denote being close orapproximate to, but not exactly. For example, the term “about” or“substantially” as used herein implies that a small margin of error ispresent, such as 1% or less than the stated amount. The term “exemplary”as used herein means “serving as an example, instance, or illustration”.Any embodiment or design described herein as “exemplary” is not to beconstrued as preferred or advantageous over other embodiments ordesigns.

FIGS. 1A and 1B schematically illustrate a conventional thermal-magneticcircuit breaker 100, wherein FIG. 1A is a schematic circuit diagram ofthe thermal-magnetic circuit breaker 100, and FIG. 1B is a perspectiveview of a housing 101 of the thermal-magnetic circuit breaker 100. Inparticular, FIG. 1A illustrates the thermal-magnetic circuit breaker 100connected between a utility power supply 110 (referred to herein as ACmains 110) and a load 120 which is connected to a branch circuit that isprotected by the circuit breaker 100. As further illustrated in FIG. 1A,the circuit breaker 100 is typically connected between a hot phase 111(referred to as “line hot”) of the AC mains 110 and a load hot line 121of the load 120, while a neutral phase 112 (referred to as “lineneutral”) of the AC mains 110 is directly connected to a load neutralline 122 of the load 120.

The circuit breaker 100 comprises an electromechanical switch 102 thatis manually opened and closed by means of a manual switch mechanism (notshown). The electromechanical switch 102 is mechanically coupled 104 toa thermal-magnetic actuator comprising a solenoid 106 connected inseries with the switch 102 and a bimetallic element 108 (which is heatedby a resistive element) also connected in series with the switch 102.The mechanical coupling 104 is configured such that an instantaneouscurrent flowing from the hot phase 111 which exceeds a first thresholdvalue (e.g., beyond the current rating of the circuit breaker 100)causes the solenoid 106 to separate the contacts of the switch 102,thereby opening the circuit and “tripping” the circuit breaker 100. Thesolenoid 106 (e.g., electromagnet) asserts a pulling force whichincreases with the current. The circuit breaker contacts are held closedby a latch. As the current in the solenoid 106 increases beyond therating of the circuit breaker, the solenoid's pull releases the latch,which causes the contacts to open by spring action.

In addition, the mechanical coupling 104 is configured such that aprolonged excess current at a second, lower threshold value causes thebimetallic element 108 to separate the contacts of the switch 102 andthereby trip the circuit breaker 100. The bimetallic element 108 isresponsive to less extreme but longer-term over-current conditions. Thethermal mechanism of the circuit breaker 100 provides a time responsefeature, that trips the circuit breaker 100 sooner for largerover-currents but allows smaller overloads to persist for a longer time.This allows short current spikes such as are produced when a motor orother non-resistive load is switched on. In this regard, the solenoid106 (electromagnet mechanism) responds instantaneously to large surgesin current (short-circuits) and the bimetallic element 108 responds toless extreme but longer-term over-current conditions. Once tripped, thecircuit breaker 100 must be manually reset using the manual switchmechanism.

As further illustrated in FIG. 1A, the line neutral 112 is typicallybonded to earth ground 114 (GND) in a circuit breaker distributionpanel, and an earth ground connection 116 is made from ground bar in thecircuit breaker distribution panel to a ground connection of the load120. The earth ground connection 116 provides an alternativelow-resistance path for ground-fault return current to flow in the eventof a ground-fault event at the load 120. The earth ground connection 116is useful for other circuit breaker or receptacle designs which provideprotections such as arc-fault sensing and arc-fault circuit interruption(AFCI), and ground-fault sensing and ground-fault circuit interruption(GFCI). Furthermore, a line neutral wire (not shown in FIG. 1A or FIG.1B) would be included in the circuit breaker 100 that is designed toprovide AFCI and GFCI protection.

FIG. 1B illustrates a conventional housing 101 for a residential circuitbreaker which is usually manufactured using molded plastic components.In some embodiments, intelligent circuit breakers are implemented usingstandard housings for residential and/or commercial applications toallow the intelligent circuit breakers to be backward compatible withexisting housings and retrofitted into existing distribution panels. Oneskilled in the art will recognize that the circuits, algorithms, heatexchangers, and other aspects of the disclosed technologies can beadjusted to various form factors required in other locations orcountries. It is contemplated herein that present approach does notrequire using traditional style breaker elements, for example,particularly without using traditional breaker housing.

In accordance with embodiments of the disclosure, intelligent circuitbreakers are designed to provide high isolation capability, while havingrelatively fast reaction times to isolate short-circuit conditions,over-current conditions, and other types of faults, more rapidly thanconventional circuit breakers. Intelligent circuit breakers are designedwith time-current characteristics that can be programmable in real time,and which are more precise with less variability as compared toconventional circuit breakers. For example, in some embodiments,intelligent circuit breakers implement low-power solid-statebidirectional switches that enable fast reaction time to isolate faultson high-energy branch circuits. Intelligent breakers are designed tocommunicate with smart devices connected to provide support for multiplepoints of failure, independent from the location of the circuit breakerinstallation, thereby allowing for a reduction in the impedance ofshort-circuited conductors.

Intelligent circuit breakers according to embodiments of the disclosureprovide added safety, expanded convenience, added energy awareness,control, energy savings, and improved situational awareness, as comparedto conventional circuit breakers. As explained in further detail below,intelligent circuit breakers implement various functionalities andcontrol circuits to implement intelligent processing, including AC mainsswitching techniques, AC-to-DC conversion techniques, internalshort-circuit trip techniques, techniques to communicate status andsensor data wirelessly to enable a variety of innovative use-cases,algorithms for detecting faults, techniques for detecting and protectionfrom internal device failures, techniques for handling new types ofloads through over-the-air updates, techniques for exchanging thermalenergy, techniques for cloud services support for remote notifications,control, monitoring and big data collection even during collapsingutility events, circuit techniques for shunt-resistor current sensing,energy metering, and over-current detection, techniques for avoidingfault conditions.

These are novel techniques in and by themselves, but their true impactin terms of addressing the challenges of improving safety, expandedconvenience, added control, energy awareness, energy savings, andimproved situational awareness lies in their combination.

FIG. 2A is a schematic block diagram of an intelligent circuit breakeraccording to an embodiment of the disclosure. In particular, FIG. 2Aschematically illustrates an intelligent circuit breaker 200 connectedbetween an AC mains 110 and a load 120. The intelligent circuit breaker200 comprises an electromechanical AC switch 202, a current sensor 204,a first voltage sensor 206, a second voltage sensor 208, AC-to-DCconverter circuitry 210, a processor 220, a processor reset switch 222,and a radio frequency (RF) transceiver 230 with an associated antenna232. The electromechanical AC switch 202 is serially connected between aline input terminal and a load output terminal of the circuit breaker200, wherein the line hot 111 of the AC mains 110 is connected to theline input terminal and the load hot 121 of the load 120 is connected tothe load output terminal. The line hot 111 of the AC mains 110 isconnected to the load hot 121 when the electromechanical AC switch 202is in a switched-closed state. In this embodiment, the line neutral 112(which, for example, is bonded to the earth ground 114 in the breakerdistribution panel) serves as a low-side voltage reference (e.g.,ground) for the electronic circuitry of the intelligent circuit breaker200.

In some embodiments, the electromechanical AC switch 202 comprises athermal-magnetic trip and switch mechanism which is the same or similarto the thermal-magnetic circuit breaker 100 discussed above inconjunction with FIG. 1A, wherein the electromechanical AC switch 202comprises a thermal switching mechanism (e.g., bimetal switch) and anelectromagnetic switching mechanism (e.g., solenoid). Theelectromechanical AC switch 202 is configured to provide an “open”circuit when either an operator manually disables the hot path using themanual switch (or actuator lever) or automatically when a faultcondition (e.g., short-circuit conditions, over-current conditions,etc.) is detected by the electromechanical AC switch 202.

The processor 220 operates in conjunction with the current sensor 204and the first and second voltage sensors 206 and 208 to performfunctions such as monitoring energy utilization and detecting faultconditions. For example, in some embodiments, the processor 220 isconfigured (via software and/or hardware) to detect the presence of afault condition in the load 120 (e.g., short-circuit condition,over-current condition, over-voltage condition, etc.), or an internalfault condition within the intelligent circuit breaker 200, and generatea control signal on a control line 202-1 to cause electrical contacts ofan electromagnetic component (e.g., solenoid) to open and therebydisconnect the line hot 111 from the load hot 121. In other embodiments,the intelligent circuit breaker 200 comprises additional sensorcircuitry and/or processing functionality to support arc-fault circuitinterruption and/or ground-fault circuit interruption functions using,for example, techniques as discussed herein.

The processor 220 can be implemented using one or more processingarchitectures. For example, the processor 220 may comprise a centralprocessing unit, a microprocessor, a microcontroller, anapplication-specific integrated circuit (ASIC), a field programmablegate array (FPGA), a system-on-chip (SOC) and other types of processors,as well as portions or combinations of such processors, which canperform processing functions based on software, hardware, firmware, etc.In some embodiments, the solid-state circuitry of the various components(e.g., 204, 206, 208, 210, 220, and/or 230) of the intelligent circuitbreaker 200 can be implemented on a single die as a system-on-chip. Insome embodiments, the solid-state circuitry of the various components(e.g., 204, 206, 208, 210, 220, and/or 230) of the intelligent circuitbreaker 200 can be implemented on one or more separate dies that areintegrally packaged as a multi-chip module (e.g., system-in-package)providing a high-density heterogeneous integrated solution.

The processor 220 utilizes the RF transceiver 230 to wirelesslycommunicate with a remote node, device, system, etc., to support remotemonitoring of energy utilization and detection of fault conditions. Theprocessor reset switch 222 is utilized to reset the status of theprocessor 220 under certain conditions, e.g., when there is a loss of DCpower to the processor 220, etc. In some embodiments, the processorreset switch 222 comprises a manual result switch that is mechanicallycoupled to the manual switch lever mechanism (e.g., actuator lever) ofthe electromechanical AC switch 202 so that a manual reset of the switchlever following a trip event also causes mechanical activation of theprocessor reset switch 222.

The current sensor 204 and the voltage sensors 206 and 208 areconfigured to sense and detect conditions that are indicative of opencircuits or damaged or failed internal components of the intelligentcircuit breaker 200 and to provide timing for the safe opening andclosing of circuits. In particular, the current sensor 204 is configuredto detect a magnitude of current being drawn by the load 120 in the hotline path through the intelligent circuit breaker 200. The currentsensor 204 can be implemented using any suitable type of current sensingcircuit including, but not limited to, a current-sensing resistor, acurrent amplifier, a Hall Effect current sensor, etc. The current sensor204 is coupled to the processor 220 by one or more data acquisition andcontrol lines 204-1.

The first and second voltage sensors 206 and 208 are configured tomonitor the voltage at different points along the hot line path throughthe circuit breaker 200. For example, as shown in FIG. 2A, the firstvoltage sensor 206 is coupled to the hot line path upstream of theelectromechanical AC switch 202 to monitor the AC supply voltage of theAC mains 110, and the second voltage sensor 208 is coupled to the hotline path downstream of the electromechanical AC switch 202 to monitorthe load voltage on the branch circuit which is connected to, andprotected by, the intelligent circuit breaker 200. The voltage sensors206 and 208 are coupled to the processor 220 by one or more dataacquisition and control lines 206-1 and 208-1, respectively.

The voltage sensors 206 and 208 can be implemented using any suitabletype of voltage sensing circuitry including, but not limited to,zero-crossing detector circuits. A zero-crossing detector is configuredto receive as input an AC waveform, compare the input AC waveform to azero reference voltage (e.g., line neutral voltage), and detect the ACwaveform transition from positive and negative, which coincides when theAC waveform crosses the zero reference voltage. In some embodiments, thezero-crossing detector circuitry is configured to generate a square waveoutput which transitions between a logic “1” and logic “0” output uponeach zero crossing detection of the AC voltage waveform. In otherembodiments, the zero-crossing detector circuitry is configured togenerate a short-lived pulse (˜3 us) having an RC-adjustable duration.

The AC-to-DC converter circuitry 210 is configured to provide DC supplypower to various circuitry and elements of the intelligent circuitbreaker 200 including the current sensor 204, the voltage sensors 206and 208, the processor 220 and the RF transceiver 230.

The AC-to-DC converter circuitry 210 remains powered during faults whenthe electromechanical AC switch 202 is in an open state. In someembodiments, the AC-to-DC converter circuitry 210 comprises sufficientstorage capacitance to power the DC subsystems immediately following autility outage such that relevant power outage or short-circuitinformation may be obtained and stored by the processor 220 as theutility power collapses, and then wirelessly transmitted to a remotenode, device, or system using the RF transceiver 230. The AC-to-DCconverter circuitry 210 may also include sufficient capacitance to powerthe DC subsystem during a load short-circuit event without beingpulled-down by the collapsing voltage of the hot line and load, suchthat the load can be intentionally disconnected to prevent damage duringout-of-range voltage events.

FIG. 2B is a schematic block diagram of an intelligent circuit breakeraccording to another embodiment of the disclosure. In particular, FIG.2B schematically illustrates an intelligent circuit breaker 201connected between an AC mains 110 and a load 120. The intelligentcircuit breaker 201 is similar to the intelligent circuit breaker 200 ofFIG. 2A, except that the intelligent circuit breaker 201 comprisescurrent sensor and energy metering circuitry 240, a fuse 250, and aninternal short-circuit switch 260. The current sensor and energymetering circuitry 240 is configured to detect a magnitude of currentbeing drawn by the load 120 in the hot line path through the circuitbreaker 201 as well as implement a programmable over-current detectionsystem and intelligent energy metering circuitry. An exemplaryembodiment of the current sensor and energy metering circuitry 240 willbe discussed below in conjunction with FIGS. 9A, 9B and 9C.

The fuse 250 is implemented to protect the circuit breaker 201 frominternal failure or to provide a simple end-of-life disablementmechanism, such as in the event of a device failure. In someembodiments, as shown in FIG. 2B, the internal short-circuit switch 260is connected between the AC hot line path of the circuit breaker 201 andthe line neutral 112, wherein the internal short-circuit switch 260 isconnected to the AC hot line path at some point between the fuse 250 andthe electromechanical AC switch 202. The internal short-circuit switch260 is responsive to control signals generated by the processor 220 andapplied to the short-circuit switch 260 over a switch control line220-1. In this configuration, the processor 220 can implement anend-of-life disablement mechanism, such as in the event of a devicefailure, wherein the processor 220 outputs a control signal on thecontrol line 220-1 to activate the internal short-circuit switch 260 andblow the fuse 250 to disable the intelligent circuit breaker 201. Inother embodiments, an end-of-life disablement mechanism can beimplemented by configuring the processor 220 to generate a controlsignal which, e.g., keeps the electromechanical AC switch 202 from beingplaced in a switched-closed state at any time after a device failure hasbeen detected, or which immediately causes the electromechanical ACswitch 202 to trip (and be placed in a switched-open state) any time anindividual attempts to turn on the breaker (via activation of the manualswitch) after a device failure has been detected.

In other embodiments, an internal short-circuit switch can beimplemented in an intelligent circuit breaker as a mechanism tointernally trigger a fault to trip the electromechanical AC switch 202.For example, in the exemplary embodiments of FIGS. 2A and 2B, aninternal short-circuit switch can be connected between the AC hot linepath and the line neutral 112 on the load side of the electromechanicalAC switch 202. The processor 220 can be configured to generate a switchcontrol signal to activate the internal short-circuit switch andgenerate a short-circuit fault condition at the load side of theelectromechanical AC switch 202 and thereby trip the electromechanicalAC switch 202. In this configuration, the processor 220 can detect theexistence of an unsafe condition or internal circuit breaker failurebased on sensor data generated by the current and/or voltage sensors240, 206, and 208, and then generate a control signal to activate theinternal short-circuit switch 260 and thereby trip the electromechanicalAC switch 202. In addition, an internal short-circuit trigger event canbe triggered in response to the processor 220 receiving a remote commandto disconnect or in response to the detection of an unsafe localcondition such as over-heating, excessive moisture, or a device failure,etc.

FIG. 3A is a schematic block diagram of an intelligent circuit breakeraccording to another embodiment of the disclosure. In particular, FIG.3A schematically illustrates an intelligent circuit breaker 300connected between an AC mains 110 and a load 120. The intelligentcircuit breaker 300 comprises an air-gap electromagnetic switch 302, asolid-state bidirectional switch 304, switch control circuitry 306 thatis configured to control operation of the air-gap electromagnetic switch302, a manual switch 307 that allows a user to manually open and closethe air-gap electromagnetic switch 302, and switch control circuitry 308that is configured to control operation of the solid-state bidirectionalswitch 304. In addition, similar to the exemplary embodiment of FIG. 2A,the intelligent circuit breaker 300 of FIG. 3A comprises a currentsensor 204, a first voltage sensor 206, a second voltage sensor 208,AC-to-DC converter circuitry 210, a processor 220, a processor resetswitch 222, and a RF transceiver 230 and associated antenna 232, whichare configured to perform functions which are the same or similar to thefunctions as discussed above. In other embodiments, as noted above, anexternal DC power supply can be implemented to provide DC power to thesolid-state circuitry and components of the intelligent circuit breaker300.

In some embodiments, the air-gap electromagnetic switch 302 comprisesany suitable type of electromagnetic trip and mechanical switchmechanism, which is configured to physically open and close a set ofelectrical contacts, wherein an air gap is created between theelectrical contacts when the air-gap electromagnetic switch 302 is in aswitched-open state. For example, the air-gap electromagnetic switch 302may comprise a latching solenoid or relay element that is responsive tocontrol signals from the switch control circuitry 306 to automaticallyopen or close the electrical contacts of the air-gap electromagneticswitch 302. In some embodiments, the switch control circuitry 306 andthe air-gap electromagnetic switch 302 are configured such that theelectrical contacts of the air-gap electromagnetic switch 302 can beautomatically opened by the switch control circuitry 306, but notautomatically closed by operation of the switch control circuitry 306.In this instance, the electrical contacts of the air-gap electromagneticswitch 302 are manually closed by operation of the manual switch 307.

In some embodiments, the switch control circuitry 308 is responsive tocontrol signals from one or more of the sensors (e.g., current sensor204, voltage sensors 206 and 208 etc.) to determine when to open theair-gap electromagnetic switch 302 in response to fault conditionsdetected by the sensors. In some embodiments, the switch controlcircuitry 306 is responsive to control signals received from theprocessor 220 (over a control line 306-1) to control the opening of theair-gap electromagnetic switch 302 in response to fault conditions suchas short-circuit faults, over-current faults, and other faults that aredetected by the processor 220 as a result of the processor 220 analyzingsensor data obtained from the current sensor 204 and the voltage sensor206 and 208.

In addition, the air-gap electromagnetic switch 302 comprises a manualswitch 307 that enables a person to manually open or close theelectrical contacts of the air-gap electromagnetic switch 302 andthereby manually place the air-gap electromagnetic switch 302 into aswitched-open or switched-closed state. The state of the manual switch307 (activated or deactivated) can be detected by the processor 220based on an electrical signal that is present on a sense line 307-1connected between the manual switch 307 and the processor 220. Thecreation of the air gap in the line path between the line hot 111 andload hot 121 provides complete isolation of the AC mains 110 from theload 120, and prevents the flow of current from the line hot 111 to theload 120 (and also prevents flow of leakage current that can begenerated by the solid-state bidirectional switch 304 when thesolid-state bidirectional switch 304 is in a switched-off state).

As shown in FIG. 3A, the air-gap electromagnetic switch 302 is connectedin series with the solid-state bidirectional switch 304 between the lineinput terminal and the load output terminal of the intelligent circuitbreaker 300. The air-gap electromagnetic switch 302 may be disposed oneither the line side (as shown in FIG. 3A) of the solid-statebidirectional switch 304 or on the load side of the solid-statebidirectional switch 304. The solid-state bidirectional switch 304comprises electrically controlled solid-state switching devices such aspower MOSFET (metal-oxide semiconductor field effect transistor) devicesand associated biasing circuitry. Exemplary embodiments of thesolid-state bidirectional switch 304 will be discussed in further detailbelow in conjunction with FIGS. 6A through 6H. The semiconductor MOSFETdevices can be silicon-based solid-state devices or silicon carbide(SiC) or gallium arsenide (GaN) based solid state devices.

The solid-state bidirectional switch 304 is controlled by the switchcontrol circuitry 308 to place the solid-state bidirectional switch 304into a switched-on state or a switched-off state in response to gatecontrol signals generated by the switch control circuitry 308. In someembodiments, the switch control circuitry 308 is responsive to controlsignals received from the processor 220 (over a control line 308-1) toswitch off the solid-state bidirectional switch 304 in response to faultconditions such as short-circuit faults, over-current faults, and otherfaults that are detected by the processor 220 as a result of theprocessor 220 analyzing sensor data obtained from the current sensor 204and the voltage sensor 206 and 208.

In other embodiments, the switch control circuitry 308 comprises controlcircuitry that is responsive to control signals generated by the currentsensor 204 (and other sensors, e.g., voltage sensors 206 and 208) inresponse to detection of fault conditions, and transmitted on a controlline 204-1 to the switch control circuitry 308. The switch controlcircuitry 308 is responsive to such control signals to generate gatingcontrol signals to control activation and deactivation of thesolid-state bidirectional switch 304. In other embodiments, the switchcontrol circuitry 308 comprises short-circuit detection circuitry whichis configured to detect a load-side short-circuit fault, andautomatically deactivate the solid-state bidirectional switch 304 inresponse to the detected short-circuit fault. An exemplary embodiment ofthe switch control circuitry 308 comprising short-circuit detectioncircuitry will be discussed in further detail below in conjunction withFIGS. 7A and 7B. In addition, the switch control circuitry 308 isconfigured to control the drive voltage of the solid-state bidirectionalswitch 304 for the purpose of controlling and minimizing leakage of thesolid-state bidirectional switch 304 when the switch 304 is in aswitched-off state.

It is to be appreciated that the implementation of the solid-statebidirectional switch 304 allows the intelligent circuit breaker 300 torapidly respond to imminent fault conditions such as over-current faultconditions, load-side short-circuit fault conditions, internal faultconditions, over-voltage conditions, etc., by rapid deactivation of thesolid-state bidirectional switch 304. Indeed, the response time fordeactivating the solid-state bidirectional switch 304 to isolate a faultcondition can be on the order of 1000 times faster than the responsetime associated with the automatic tripping of an electromechanical ACswitch to isolate the fault condition (e.g., on the order of severalmilliseconds), as the solid-state state bidirectional switch 304 cantransition from a switched-on state to a switched-off state on the orderof microseconds or nanoseconds. As a further advantage, the solid-statebidirectional switch 304 has a time-current characteristic profile thatis more precise and repeatable as compared to a conventionalelectromechanical circuit breaker. This allows the current which isconducted by the solid-state bidirectional switch 304 to be moreprecisely controlled, as compared to conventional electromechanicalcircuit breakers which have time-current characteristics that vary overtheir life-time.

In some embodiments, the control logic implemented by the processor 220of the intelligent circuit breaker 300 is configured to issue switchcontrol signals to the switch control circuitry 306 so that the air-gapelectromagnetic switch 302 is placed in a switched-open state inresponse to the solid-state bidirectional switch 304 being placed into aswitched-off state. In some embodiments, the control logic implementedby the processor 220 is configured to issue switch control signals tothe switch control circuitry 306 so that the air-gap electromagneticswitch 302 is placed in a switched-closed state prior to placing thesolid-state bidirectional switch 304 into a switched-on state. Inaddition, the processor 220 is configured to monitor and detect for amanual switch opening event wherein the manual switch 307 of the air-gapelectromagnetic switch 302 is actuated to manually open the electricalcontacts of the air-gap electromagnetic switch 302. In response to themanual switch opening event, the processor 220 will generate and outputa control signal to the switch control circuitry 308 to place thesolid-state bidirectional switch 304 into a switched-off state.

The switch timing control scheme as outlined above prevents or minimizesthe generation of electrical arcs between the electrical contacts of theair-gap electromagnetic switch 302 by ensuring that (i) the air-gapelectromagnetic switch 302 is placed in a switched-closed state prior toplacing the solid-state bidirectional switch 304 into a switched-onstate, and that (ii) the solid-state bidirectional switch 304 isautomatically placed in a switched-off state in response to detection ofa manual operator disconnect of the air-gap electromagnetic switch 302and thereby deactivate the solid-state bidirectional switch 304 prior tothe opening of the electrical contacts of the air-gap electromagneticswitch 302. In another embodiment, the switch control scheme isconfigured to operate the intelligent circuit breaker 300 in a “standby”state, wherein the solid-state bidirectional switch 304 is in aswitched-off state, and the air-gap electromagnetic switch 304 in aswitched-closed state.

With such switch control configuration, the electrical contacts of theair-gap electromagnetic switch 302 are configured to support high energyflow in a switched-closed state, but may be designed for movement onlyduring low-current flow conditions to prevent or minimize arcing betweenthe electrical contacts. For example, a switch control scheme can beimplemented in which the air-gap electromagnetic switch 302 is actuatedwhen the magnitude of the current on the hot line path is less than apre-selected value. The prevention of arcing within the air-gapelectromagnetic switch 302 enables miniaturization of the air-gapelectromagnetic switch 302.

The implementation of the air-gap electromagnetic switch 302 providesadditional safety features for the intelligent circuit breaker 301. Forexample, the air-gap electromagnetic switch 302 provides a fail-safemechanism for fault isolation in the event that the solid-statebidirectional switch 304 fails. By analyzing the real-time sensor dataobtained from the various sensors 204, 206 and 208, the processor 220can be configured to detect a failure state of the solid-statebidirectional switch 304 or otherwise detect potential over-current orshort-circuit fault conditions. In such instance, the processor 220 cangenerate and output a control signal to the switch control circuitry 306to place the air-gap electromagnetic switch 302 into a switched-openstate.

In some embodiments, the current sensor 204 comprises a sense resistorthat is connected in series in the hot line path. As explained infurther detail below, the sense resistor is configured to generate aburden voltage or sense voltage as a result of load current flowingthrough the sense resistor, wherein the burden voltage or sense voltageis measured and processed by one or more detection circuits (e.g.,current sensor circuit, short-circuit detection circuit, energy meteringcircuit, etc.) to detect fault conditions and to control the solid-stateswitch directly without the assistance of the processor. This allows forfaster reaction time by avoiding the indeterminate time of the processoror CPU response.

In addition, the air-gap switch 302 provides galvanic isolation betweenthe AC mains 110 and the load 120 when the air-gap switch 302 is placedin a switched-open state. With the air gap formed, no current can flowfrom the AC mains 110 to the load 120. Such galvanic isolation guardsagainst the unwanted flow of current due to leakage current of thesolid-state bidirectional switch 304 when the solid-state bidirectionalswitch 304 is in a switched-off state.

As with other embodiments discussed herein, the processor 220 can beimplemented using one or more processing architectures (e.g., CPU,microprocessor, a microcontroller, ASIC, etc.). In some embodiments, thesolid-state circuitry of the various components (e.g., 204, 206, 208,210, 220, 230, 306, and/or 308) of the intelligent circuit breaker 300can be implemented on a single die as a system-on-chip. In someembodiments, the solid-state circuitry of the various components (e.g.,204, 206, 208, 210, 220, 230, 306, and/or 308) of the intelligentcircuit breaker 230 can be implemented on one or more separate dies thatare integrally packaged as a multi-chip module (e.g., system-in-package)providing a high-density heterogeneous integrated solution.

FIG. 3B is a schematic block diagram of an intelligent circuit breakeraccording to another embodiment of the disclosure. In particular, FIG.3B schematically illustrates an intelligent circuit breaker 301connected between an AC mains 110 and a load 120. The intelligentcircuit breaker 301 comprises a combination of components of theintelligent circuit breakers 201 and 300 (FIGS. 2B and 3A) and thus, adetailed description of the various components and associatedfunctionalities will not be repeated. The intelligent circuit breaker301 comprises a snubber 310 that is connected between the hot line pathand neutral line path to protect the internal components from damage dueto energy kick-back from inductive loads. The snubber 310 may bedisposed on the line and/or load side of the switches 302 and 304. Asnubber located on the line side of the switches 302 and 304 allows thesnubber to only protect the internal circuits when the switches 302 and304 are in switched-open and switched-on states, respectively. However,the snubber 310 located on the load side of the switches 302 and 304 asshown in FIG. 3B helps to eliminate the possibility of an arc occurringwithin the air-gap electromagnetic switch 302 during an inductive loadkick-back event. It is to be understood that a snubber can beimplemented in the intelligent circuit breaker embodiments of FIGS. 2A,2B, and 3A.

In other embodiments, an external DC power supply can be implemented toprovide DC power to the solid-state circuitry and components of theintelligent circuit breakers 200, 201, 300, and 301 of FIGS. 2A, 2B, 3Aand 3B (as well as other embodiments of circuit breakers discussedbelow). For example, a distribution panel in which an intelligentcircuit breaker is mounted can have a DC battery and a DC power bus thatis configured to distribute DC power to the intelligent circuit breakerswithin the distribution panel. In this instance, the DC battery can becoupled to an AC-to-DC converter that is configured to convert the ACpower of the AC mains 110 to DC power that charges the DC battery.

While the exemplary embodiments of FIGS. 2A, 2B, 3A and 3B illustrate aprocessor reset switch 222 for resetting the processor 220, it is to beunderstood that the processor reset switch 222 is an optional feature,and that other mechanisms can be implemented for effecting a processorreset. In some embodiments, the processor 220 comprises an internalreset circuit that is configured to reset the processor 220 undercertain circumstances such as when there is a loss of DC power to theprocessor 220 or when there is an internal fault condition of theprocessor 200. In some embodiments, the processor is configured togenerate a “CPU_OK” signal which is output on the control lines 306-1and 308-1 to the switch control circuitry 306 and 308. The CPU_OK signalprovides an indication of whether or not the processor 220 andassociated software is operating normally. When the CPU_OK signalindicates that the processor 200 and/or associated software is notoperating normally, the switch control circuitry 306 and 308 willautomatically place the solid-state bidirectional switch 304 into aswitched-off state and then place the air-gap electromagnetic switch 302into a switched-open state (to create the air-gap for galvanicisolation). This provides a hardware fail-safe mechanism to ensure thatthe intelligent circuit breaker is not servicing a load under conditionswhere the processor 220 or a subsystem thereof is not operatingcorrectly.

For example, in some embodiments, the internal reset circuit of theprocessor 220 comprises a Watchdog timer and suitable architectedsoftware that is configured to service the Watchdog timer (e.g., resetthe Watchdog timer) when all subsystems within the firmware of theprocessor 220 are determined to be operating correctly. In someembodiments, the Watchdog timer comprises a resistor/capacitor networkwhich implements a unique clock. When the Watchdog timer is enabled, thetimer counts from an initial value to final count value. If the Watchdogtimer is not initialized to the initial count value before reaching thefinal count value, the processor 220 will be reset. The processor 220will be reset because of a loss of AC (thus DC) power, or an internalfault condition that causes the Watchdog timer to reach the final countvalue in which case a control signal is generated which causes theprocessor 220 to be reset.

More specifically, in some embodiments, the internal reset circuit ofthe processor 220 operates as follows. When DC power is first applied tothe processor 220, the processor will perform a self-check andinitialization routine. If the self-check and initialization routine aresuccessfully completed, the processor 220 will output a logic “1” CPU_OKcontrol signal to indicate that the processor 220 and embedded softwareare operating correctly. The logic “1” CPU_OK control signal is input tothe switch control circuitry 306 and 308 to indicate that the switches302 and 304 can be safely activated to service the load 120. On theother hand, a logic “0” CPU_OK control signal indicates to the switchcontrol circuitry 306 and 306 that the switches 320 and 304 should bedeactivated or should not be activated (if deactivated at the time thatCPU_OK is asserted to a logic “0” level). Upon reset of the processor220 (e.g., a power-up reset or a forced reset due to a determinedinternal processor fault), the control signal CPU_OK is held at a logic“0” level until the processor 220 is reset and determined to be fullyfunctional and operating as expected.

The software of the processor 220, as part of its normal operation,continuously monitors several points in the firmware to ensure that allsubsystems of the processor 220 are properly operating as excepted. Ifall monitored points are determined to be operating correctly, then theWatchdog timer is serviced (e.g., counter is reset to the initialvalue). If any one of the monitored points is determined to benonfunctional or operating incorrectly, the Watchdog timer will not beserviced, and the Watchdog timer will eventually reach its maximum countvalue. In some embodiments, the Watchdog timer has a count sequence withdefines approximately 1 second of time. If the Watchdog timer is notserviced by the reset control software of the processor 220, theWatchdog timer will “fire” after ˜1 second and reset the processor 220,which causes the CPU_OK control signal to transition to a logic “0”level. The transition of the CPU_OK signal from logic “1” to logic “0”triggers the switch control circuitry 306 and 308 to place thesolid-state bidirectional switch 304 into a switched-off state, andplace the air-gap electromagnetic switch 302 into a switched-open state.

Furthermore, in some embodiments, as part of the reset sequence of theprocessor 220, there is a hardware indication (designed into theprocessor 220) which indicates whether the processor reset was caused bya Watchdog timer reset or a power-on-reset. If the processor reset iscaused by a power-on-reset, the firmware of the processor 220 willproceed with a normal startup initialization process. On the other hand,if the processor reset is triggered by the Watchdog timer, the firmwareof the processor 220 will proceed with a “Recover from a Watchdog timerreset” initialization path instead of the normal startup initialization.To the user, a Watchdog timer reset appears like a normal over-current“Trip” condition (with communication to the cloud or a remote computingdevice that the processor reset was caused by an internal Watchdog timerreset).

With this reset sequence, the firmware will determine whether the numberof consecutive Watchdog timer resets has exceeded a predefined thresholdnumber (e.g., 5). If the number of consecutive Watchdog timer resets isdetermined to exceed the predefined threshold number, an internalfailure or internal fault condition will be declared and the intelligentcircuit breaker will be disabled until it is serviced and the counter isreset. In this instance, the processor firmware will declare an internalfailure and report the error via cloud notification, status LEDs, andother available user interfaces, and not allow the intelligent circuitbreaker to be manually turned ON until it is serviced. On the otherhand, the intelligent circuit breaker can be manually reset following aWatchdog timer reset if the number of consecutive Watchdog timer resetshas not exceeded the predetermined threshold number.

In other words, a Watchdog timer reset event appears like a “normalover-current trip” by design and is the result of the processor firmwarewhich executes immediately following a reset. The processor firmwarewill determine if the processor reset was caused by the Watchdog timer,and if so, recovery is performed by emulating a “trip” event, withcommunication to the cloud indicating the Watchdog timer reset event,and allowing normal operation to continue once the air-gap switch 302 isplaced into a switched-closed state either manually or automatically viaa controls signal, if so provisioned. If the processor 220 is no longerfunctional once the Watchdog timer fires (or when power is (re)applied),the unit will be totally non-functional, with the AC to the loadguaranteed to be OFF by design. In a rare case where the processor 220becomes non-functional immediately following a Watchdog timer reset,there will be no communication of the event to the cloud, because thecommunication to the cloud is part of the “recovery” path during theinitialization.

The exemplary embodiments of the intelligent circuit breakers of FIGS.2A, 2B, 3A and 3B provide various advantages over conventional circuitbreaker designs. For example, the implementation of voltage and currentsensors, processors, and a wireless communications subsystem provide theability of the intelligent circuit breaker to sense operating conditionsof circuit breaker and load and wirelessly communicate which breaker hastripped making it far easier to identify within the circuit breakerpanel. This may be extended with the addition of an LED signal at thefront-panel controlled by a processor. The feature is enabled with theaddition of the AC-to-DC converter circuit which remains powered duringfault events.

Furthermore, intelligent circuit breakers are capable of saving time inlife-safety applications such as when circuits are, or are nearly,over-loaded in hospitals and similar applications such as militarycommand and control facilities. Maintenance technicians or electriciansin such an environment can be wirelessly notified of an impending orexisting fault with information to direct them to offending load withoutthe local affected personnel having to reach out to maintenance forsupport. The speed at which the load is analyzed and cleared and thebreaker re-energized, or prevented from opening, may be critical to thesuccessful treatment of patients or the continuation of critical jobfunctions. In some embodiments, wireless communication with anintelligent circuit breaker allows a technician or electrician toremotely re-energize the load using predetermined commands to remotelycontrol the intelligent circuit breaker.

As a third example, the solid-state switch technology that isimplemented in the intelligent circuit breakers of FIGS. 3A and 3B, forexample, is capable of disconnecting a fault roughly 1000 times fasterthan the electro-mechanical equivalent in FIG. 1A, and with addedreliability due to the arc-free non-moving nature of solid-stateelectronics. The added speed further reduces the likelihood of damage toa circuit, an electrical device, a load, fire, and personal harm. Insome embodiments, the solid-state switch is opened in less than onecycle during the collapse of AC power that occurs during a short-circuitcurrent at the load.

FIG. 4A is a schematic block diagram of an AC-to-DC converter circuit400 which can be implemented in an intelligent circuit breaker,according to an embodiment of the disclosure. The AC-to-DC convertercircuit 400 comprises an architecture which does not require a rectifierto generate DC voltage. The AC-to-DC converter circuit 400 comprises aninrush protection circuit 410, a sampling circuit 420, a switch drivercircuit 430, a control switch and clamp circuit 440, a storage circuit450, a voltage regulator circuit 460, and a galvanic isolation circuit470. The AC-to-DC converter circuit 400 generates a DC supply voltagethat is applied to load circuitry 402.

The inrush protection circuit 410 is configured to limit the magnitudeof input current to the AC-to-DC converter circuit 400. The samplingcircuit 420 is configured to sample the AC supply voltage waveform of ACmains 110. The sampling circuit 420 outputs sampled voltages to theswitch driver circuit 430. The switch driver circuit 430 is configuredto apply a control voltage to a control switch of the control switch andclamp circuit 440. The control switch and clamp circuit 440 isconfigured to supply power to the storage circuit 450 in response to thecontrol voltage applied by the switch driver circuit 430. The storagecircuit 450 comprises a voltage storage element (e.g., capacitor) thatis configured to store a DC voltage that is applied to the voltageregulator circuit 460. The voltage regulator circuit 460 is configuredto generate a regulated DC supply voltage to the load circuitry 402.

In some embodiments, the switch driver circuit 430 receives a feedbackvoltage 480 from the storage circuit 450 and generates the controlvoltage that is applied to the control switch and clamp circuit 440based, at least in part, on the feedback voltage 480.

In some embodiments, the feedback voltage 480 can be eliminated, and theAC-to-DC converter circuit 400 operates as a feed forward converter inwhich the storage element of the storage circuit 450 is controlled fromthe forward side elements 420, 430 and 440.

In some embodiments, the AC-to-DC converter circuitry 400 implements afeedback control circuit 490 from the load circuitry 402 to the switchdriver circuit 430 to support both feed forward and feedback control. Insome embodiments, the balance of feed forward and feedback control isdetermined by the feedback voltage 480 and the selection of componentsin the sampling circuitry 420. In some embodiments, a balance betweenfeedforward and feedback control is configured according to resistorelements in the sampling circuitry 420 and the feedback voltage 480. Inother embodiments, variable elements are utilized to enable adjustmentof the feedforward and feedback control. In such embodiments, thefeedback circuit 490 would comprise galvanic isolation between theswitch driver circuit 430 and the load circuitry 402.

FIG. 4B is a schematic circuit diagram of the AC-to-DC converter circuitof FIG. 4A, according to an embodiment of the disclosure. In theexemplary embodiment of FIG. 4B, the inrush protection circuitry 410comprises a first input resistor 411 connected to the line hot 111 ofthe AC mains 110 and a second input resistor 412 connected to the lineneutral 112 of the AC mains 110. In other embodiments, for high-powerand high-efficiency applications, the inrush protection circuitry 410comprises switch elements that are configured to allow current to flowthrough the resistors 411 and 412 at startup, and then bypass theresistors 411 and 412 once steady state operation is reached. In otherembodiments, the inrush protection circuitry 410 comprises first andsecond inductor elements in place of the first and second resistors 411and 412.

The sampling circuitry 420 comprises a plurality of resistors 421, 422,423, and 424 which are connected to various nodes N1, N2, N3, and N4 asshown. The resistors 421, 422, and 423 form a voltage divider networkfor sampling the input AC waveform, wherein the voltage divider networkcomprises a feedback node N2 and an output node N3. The resistor 424 isconnected between the feedback node N2 and an output node N4 of thestorage circuitry 450 to provide a feedback voltage from the storagecapacitor 452. The switch driver circuitry 430 comprises a resistor 431connected between nodes N1 and N5, and a switch element 432. The controlswitch and clamp circuitry 440 comprises a control switch element 441, aresistor 442, and a Zener diode 443. The storage circuitry 450 comprisesa diode 451 and a storage capacitor 452. The voltage regulator circuitry460 comprises a switch element 461, a resistor 462, a Zener diode 463,and a capacitor 464.

In some embodiments, the switch elements 432, 441 and 461 comprisen-type enhancement MOSFET devices with gate G, drain D and source Sterminals as shown in FIG. 4B. In other embodiments, the switch elements432, 441 and 461 may be implemented using bipolar transistors ormicroelectromechanical switches. As shown in FIG. 4B, the switch element443 comprises a gate terminal G connected to the output node N3 of thevoltage divider network of the sampling circuitry 420, a drain terminalD connected to an output node N5 of the switch driver circuitry 430, anda source terminal S connected to an output node N3 of the inrushprotection circuitry 410. The drain terminal D of the switch element 432is coupled to the output node N1 of the inrush protection circuitry 410through the resistor 431.

The control switch 441 comprises a drain terminal D connected to theoutput node N1 of the inrush circuitry 410, a gate terminal G connectedto the output node N5 of the switch driver circuitry, and a sourceterminal S connected to an input (i.e., anode of diode 451) of thestorage circuitry 450. The Zener diode 443 is connected between the gateterminal G and source terminal S of the control switch 441, with acathode of the Zener diode 443 connected to the gate terminal G of thecontrol switch 441 and an anode of the Zener diode 443 connected to thesource terminal S of the control switch 441.

The switch element 461 of the voltage regulator circuitry 460 comprisesa drain terminal D connected to the output node N4 of the storagecircuitry 450, a gate terminal G connected to a node N7 between theresistor 462 and the Zener diode 463, and a source terminal S connectedto an output node N8 of the voltage regulator circuitry 460. Thecapacitor 464 is connected between the output node N8 of the voltageregulator circuitry 460 and the output node N6 of the inrush protectioncircuitry 410.

The resistor 424 (or sense resistor) is connected between the outputnode N4 of the storage circuitry 450 to provide a feedback voltage thatis applied to the feedback node N2 of the sampling circuitry 420 throughthe resistor 424. The feedback path provided by the connection of theresistor 424 between nodes N4 and N2 provides an exemplary embodiment ofthe feedback voltage 480 as shown in FIG. 4A, wherein the charge of thestorage capacitor 452 is utilized, in part, to generate a controlvoltage at the output node N3 of the sampling circuitry 420 connected tothe gate terminal G of the switch element 432 of the switch drivercircuitry 430.

The switch element 432 is driven by a gate control voltage generated atthe output node N3 of the voltage divider network of the samplingcircuitry 420. The gating of the switch element 432 controls operationof the control switch 441 of the switch driver circuitry 430. Theresistance values of the resistors 421, 422, 423, and 424 are selectedsuch that the voltage on node N3 of the voltage divider network, whichis applied to the gate terminal G of the switch element 432 in theswitch driver circuitry 430, will turn the switch element 432 ON and OFFand thereby synchronously turn the control switch element 441 OFF andON. The control switch element 441 is thereby driven to output apreselected timed output pulse to charge the storage capacitor 452.

The peak output current of the control switch 441 is clamped to apreselected value based on a preselected value of the Zener voltage(i.e., reverse breakdown voltage) of the Zener diode 443, wherein themaximum gate-to-source voltage (V_(GS)) is limited by the Zener voltageof the Zener diode 443. The pulsed output from the control switch 441operates to turn on the diode 451 and supply charge to the node N4 tocharge the storage capacitor 452. The feedback provided by the resistor424 connected between the output node N4 of the storage circuitry 450and the feedback node N2 of the sampling circuitry 420 serves to drivethe switch driver circuit 430 to maintain the storage capacitor 452 to aconstant charge.

The switch element 432 and control switch 441 are activated, eitheropened or closed, in synch with the AC voltage input. The AC-to-DCconverter circuit 400 provides a low voltage output with pulsemodulation at the frequency of the incoming AC source. The switches 432and 441 are activated, either opened or closed, at voltages that arenear, within the threshold voltages for the switches 432 and 441, of thezero crossing of the AC source. The output node N4 of the storagecircuitry 450 is applied to an input of the voltage regulator circuitry460 and then the load circuit 402. The capacitor 464 provides storagecapacity to buffer and thereby smooth the output from the AC-to-DCconverter 400 to the load circuitry 402.

In summary, the exemplary AC-to-DC converter circuits 400 as shown inFIGS. 4A and 4B comprise the inrush protection circuit 410, the voltagesampling circuit 420, the switch driver circuit 430, the control switchand clamp circuit 440, the storage circuit 450, and the voltageregulator circuit 460. The selection of components in the voltagesampling circuit 420 determine the timing of the switch driver 430. Theselection of components of the control switch and clamping circuit 440determine a peak voltage and current for out pulses. Power output iscontrolled by selection of both the peak current and the pulse timing.Feedback from the storage element 452 through the voltage samplingcircuit 420 is utilized to select the pulse timing. The AC-to-DCconverter circuit 400 operates in sync with the AC voltage waveform ofthe AC mains 110.

In other embodiments, the AC-to-DC converter circuitry shown in FIGS.2A, 2B, 3A, and 3B (and other embodiments of intelligent circuitbreakers as discussed below) can be implemented using the same orsimilar DC power conversion techniques as disclosed in the followingco-pending applications: (1) U.S. patent application Ser. No.16/092,263, filed on Oct. 9, 2018 (Pub. No.: US 2019/0165691), entitledHigh Efficiency AC to DC Converter and Methods; and (2) U.S. patentapplication Ser. No. 16/340,672, filed on Apr. 9, 2019 (Pub. No.: US2019/0238060), entitled High-Efficiency AC Direct to DC ExtractionConverter and Methods, the disclosures of which are all fullyincorporated herein by reference.

FIG. 5 is a schematic circuit diagram of an AC-to-DC converter circuit500 which can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure. In particular, FIG. 5schematically illustrates an exemplary embodiment of a sample and holdAC-to-DC converter circuit 500 which can be implemented using techniquesas disclosed in U.S. patent application Ser. No. 16/029,546, filed onJul. 7, 2018, entitled Method and Apparatus for Signal Extraction withSample and Hold and Release, the disclosure of which is fullyincorporated herein by reference. The AC-to-DC converter circuit 500 isconfigured to generate a DC supply voltage from an AC voltage waveformof the AC mains 110. The AC-to-DC converter circuit 500 comprises firstand second resistors 501 and 502, a first switch 510, a second switch512, a controller 520, a diode 530, a storage capacitor 540, a voltageregulator 550, and an output capacitor 560. In the exemplary embodimentof FIG. 5, the first and second switches 510 and 512 comprise N-typeenhancement MOSFETs having gate terminals G, drain terminals D, andsource terminals S as shown.

The resistors 501 and 502 form a voltage divider circuit having anoutput node N1 that drives the gate terminal G of the first switch 510.The source terminal S of the first switch 510 is connected toneutral/ground 114, and the drain terminal D of the first switch 510 isconnected to the gate terminal G of the second switch 512 and to thecontroller 520. The drain terminal D of the second switch 512 isconnected to the line hot 111, and the source terminal S of the secondswitch 512 is connected to an input of the controller 520. Thecontroller 520 has an output that is connected to an anode of the diode530. The diode 530 and the storage capacitor 540 form a storage circuitsimilar to that shown in FIG. 4B. In addition, the voltage regulator 550and the output capacitor 560 form a voltage regulator circuit similar tothat shown in FIG. 4B.

Exemplary embodiments of the solid-state bidirectional switch 304 asshown in FIGS. 3A and 3B (and as implemented in other exemplaryembodiments discussed below) will now be discussed in further detail inconjunction with FIGS. 6A through 6H. For example, FIG. 6A is aschematic circuit diagram of a solid-state bidirectional switch 600-1that can be implemented in an intelligent circuit breaker, according toan embodiment of the disclosure. In particular, FIG. 6A illustrates anexemplary embodiment of the solid-state bidirectional switch 304 shownin FIGS. 3A and 3B for controlling AC power delivered from the AC mains110 to the load 120. The solid-state bidirectional switch 600-1 isconfigured to allow a bidirectional flow of current between the AC mains110 and load 120 (i.e., conduct positive current or negative current)when the solid-state bidirectional switch 600-1 is in switched-on state,and block positive or negative current flow between the AC mains 110 andthe load 120 when the solid-state bidirectional switch 600-1 is in aswitched-off state.

The solid-state bidirectional switch 600-1 comprises a first MOSFETswitch 601 and a second MOSFET switch 602 which are connectedback-to-back in series along the hot line path between the line hot 111and the load hot 121. In some embodiments, the first and second MOSFETswitches 601 and 602 comprise power MOSFET devices and, in particular,N-type enhancement MOSFET devices, having gate terminal (G), drainterminals (D), and source terminals (S) as shown. In the exemplaryembodiment of FIG. 6A (and other embodiments discussed herein), thesolid-state bidirectional switch 600-1 is implemented using twoN-channel MOSFET switches 601 and 602 with commonly connected sourceterminals.

The first and second MOSFET switches 601 and 602 comprises intrinsicbody diodes 601-1 and 602-1, respectively, which represent the P-Njunctions between the P-type substrate body to N-doped drain regions ofthe MOSFET devices. The body diodes 601-1 and 602-1 are intrinsicelements of the MOSFET switches 601 and 602 (i.e., not discreteelements) and, thus, are shown with dashed-line connections. It is to benoted that the intrinsic body-to-source diodes of the MOSFET switches601 and 602 are not shown as they are shorted out by the connectionsbetween the source regions and the substrate bodies (e.g., N+source andP body junction are shorted through source metallization).

The solid-state bidirectional switch 600-1 further comprises first andsecond resistors 603 and 604, first and second rectifier diodes 605 and606, a Zener diode 608, and a single pole, single throw (SPST) switchelement 607. The first resistor 603 and the first rectifier diode 605are serially connected between the drain terminal (D) and the gateterminal (G) of the first MOSFET switch 601. The second resistor 604 andthe second rectifier diode 606 are serially connected between the drainterminal (D) and gate terminal (G) of the second MOSFET switch 602. Theswitch 607 and the Zener diode 608 are connected in parallel between thecommonly connected source terminals (S) and the commonly connected gateterminals (G) of the first and second MOSFET switches 601 and 602,wherein an anode of the Zener diode 608 is connected to the sourceterminals, and a cathode of the Zener diode 608 is connected to the gateterminals.

The Zener diode 608 comprises a reverse breakdown voltage (referred toas “Zener voltage” V_(Z)) which is greater than a threshold voltage,V_(T), of the power MOSFET switches 601 and 602. During a switched-onstate of the solid-state bidirectional switch 600-1, the Zener diode 608is “reversed” biased through a first bias branch circuit comprising theserially-connected first resistor 603 and first rectifier diode 605 orthrough a second bias branch circuit comprising the serially-connectedsecond resistor 604 and second rectifier diode 606. The first and secondrectifier diodes 605 and 606 are coupled to the drain terminals D of thepower MOSFET switches 601 and 602, respectively, and protected by thefirst and second resistors 603 and 604 which serve to limit an amount ofcurrent that flows through the first and second rectifier diodes 605 and606, respectively.

The solid-state bidirectional switch 600-1 generally operates asfollows. When the switch 607 is in an “open” state as shown in FIG. 6A,the first bias branch (603-605) and the second bias branch (604-606)provide “reverse bias” for the Zener diode 608 when either drainterminal D exceeds the Zener voltage, thereby placing the power MOSFETswitches 601 and 602 in an “on” state. When the switch 607 is in a“closed” state, the switch 607 shunts the bias current from the firstand second bias branches (603-605) and 604-608 to the source S terminalsof the power MOSFET switches 601 and 602, which causes the MOSFETswitches 601 and 602 to be placed in an “off” state. In this circuitconfiguration, a “turn-on” time constant is dictated by the value of thecurrent limiting resistors 603 and 604 and the gate-to-sourcecapacitance of the power MOSFET switches 601 and 602, while a “turn-off”time constant is dictated by the intrinsic capacitances of the MOSFETswitches 601 and 602 and the on-resistance of switch 607. The “turn-on”and “turn-off” time constants can be designed to be much shorter thanthe period of the AC mains 110, which allows the solid-statebidirectional switch 600-1 to operate in both an on-off and aphase-control mode. In practice, however, the Zener diode 608 may neverreach its Zener voltage, and the gate-source voltage of the MOSFETswitches 601 and 602 will rarely exceed the threshold voltage, V_(T).Thus, neither MOSFET switch 601 and 602 may be fully “on” resulting inexcess power dissipation in the units and reduced current supplied tothe load 120.

FIG. 6B illustrates active elements of the solid-state bidirectionalswitch 600-1 of FIG. 6A during a positive half cycle of the supplyvoltage waveform of the AC mains 110 applied to the solid-statebidirectional switch 600-1. When the switch 607 is in an open state toallow the first MOSFET switch 601 to turn on, the gate voltage of thefirst MOSFET switch 601 begins to follow the positive excursion of thesupply voltage waveform of the AC mains 110 when the supply voltageincreases from zero volts. When the gate voltage reaches the thresholdvoltage of first MOSFET switch 601, current begins to flow to the load120 and the body diode 602-1 of the second MOSFET switch 602 is forwardbiased. The source voltage of first MOSFET switch 601 “follows” theincreasing gate voltage, but lagging behind by the value of thethreshold voltage plus an additional bias to account for the currentsupplied to the load 120. This condition is maintained until the voltagewaveform of AC mains 110 becomes negative. Consequently, thedrain-to-source voltage of first MOSFET switch 601 never falls below thethreshold voltage, regardless of the drain-to-source resistance of thefirst MOSFET switch 601, such that the power dissipated in the firstMOSFET switch 601 is (I_(D)×V_(T)), where I_(D) is the drain current. Ifthe gate voltage is boosted well beyond the threshold voltage, thedissipated power is given by (I_(D) ²×r_(ds)), where r_(ds) is the “on”resistance of the first MOSFET switch 601, wherein the value of (I_(D)²×r_(ds)) can be significantly smaller than the value of (I_(D)×V_(T)).

On the other hand, during a negative half-cycle of the supply voltagewaveform of the AC mains 110 applied to the solid-state bidirectionalswitch 600-1, the active components of the solid-state bidirectionalswitch 600-1 include the body diode 601-1 of the first MOSFET switch601, the Zener diode 608, the second MOSFET switch 602, and the secondbranch elements 604 and 606. The gate voltage of the second MOSFETswitch 602 starts at 0V and begins to follow the source voltage negativeonce the source voltage drops to the negative threshold voltage (−V_(T))wherein current begins to flow through the load 120 and the body diode601-1 of the first MOSFET switch 601 is forward biased. The drainvoltage of the second MOSFET switch 602 is effectively clamped to thegate voltage, so that the drain-to-source voltage V_(DS) is remains at−V_(T) until the supply voltage waveform of the AC mains 110 becomespositive. Consequently, V_(DS) of the second MOSFET switch 602 neverfalls below the threshold voltage except around the zero-crossing of thepower supply voltage waveform of the AC mains 110, regardless of thedrain-to-source resistance of the second MOSFET switch 602, and thepower dissipated is (I_(D)×V_(T)) in the negative half-cycle.

FIG. 6C is a schematic circuit diagram of a solid-state bidirectionalswitch 600-2 that can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure. The solid-statebidirectional switch 600-2 is similar in circuit configuration to thesolid-state bidirectional switch 600-1 of FIG. 6A, except that thesolid-state bidirectional switch 600-2 implements a single pole,double-throw (SPDT) switch element 612 in place of the SPST switch 607,and further comprises a capacitor 613 that is connected in parallel withthe Zener diode 608. The double pole switch 612 is controlled by aswitch control circuit 610 which is coupled to the double pole switch612 by a control line 610-1. In some embodiments, the switch controlcircuit 610 comprises an embodiment of the switch control circuitry 308shown in FIGS. 3A and 3B. The switch control circuit 610 operates thedouble pole switch 612 to selectively connect the gate G terminals ofthe first and second MOSFET switches 601 and 602 to (i) the source Sterminals of the first and second MOSFET switches 601 and 602 (“position1”) or to (ii) bias circuitry comprising the first and second resistors603 and 604, the first and second rectifier diodes 605 and 606, and thecapacitor 613 (“position 2”).

When the switch 612 is set to position 1, the first and second MOSFETswitches 601 and 602 are maintained in an “off” state. The switchcontrol circuit 610 is configured to maintain the switch 612 in position1 until the supply voltage waveform of the AC mains 110 exceeds apre-established trigger level, V_(TRIG), whereupon the switch 612 is setto position 2. In this instance, during a positive half cycle of the ACmains 110, the switch control circuit 610 operates the switch 612 tomaintain the first and second MOSFET switches 601 and 602 in an “off”state until the AC supply voltage waveform reaches V_(TRIG), whichallows the bias circuitry 603, 605, 613 to charge to V_(TRIG) while thesource S terminal of the first MOSFET switch 601 remains at 0 volts.

When switch 612 is placed into position 2, the bias voltage, V_(TRIG),is applied to the gate terminal of the first MOSFET switch 601, wherebythe bias voltage value can be much larger than the threshold voltage,V_(T). The source terminal of first MOSFET switch 601 begins chargingtowards V_(TRIG)-V_(T), and part of this voltage step is coupled to thegate terminal of the first MOSFET switch 601 through the capacitor 613.This increases the gate bias well beyond V_(TRIG) so that it exceeds theAC source 601 voltage value. Thus, the first MOSFET switch 601 reaches astate where the drain-to-source voltage is nearly zero, while thegate-to-source voltage is larger than V_(TRIG). In this state, the firstMOSFET switch 601 exhibits its minimum channel resistance, R_(DS), andmaximum voltage appears across load 120.

FIG. 6D is a schematic circuit diagram of a solid-state bidirectionalswitch 600-3 that can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure. The solid-statebidirectional switch 600-3 is similar in circuit configuration to thesolid-state bidirectional switch 600-2 of FIG. 6C, wherein the doublepole switch 612 is implemented using first and second control switches621 and 622 that are controlled by a switch control circuit 620. Theswitch control circuit 620 comprises a first control line 620-1 that iscoupled to the first control switch 621, and a second control line 620-2that is coupled to the second control switch 622. In some embodiments,the first and second control switches 621 and 622 comprisephototransistors (e.g., optical bipolar junction transistors).

The switch control circuit 620 monitors the voltage level of the supplyvoltage waveform on the line hot path 111. While the voltage levelremains below the predetermined trigger level trigger level, V_(TRIG),the switch control circuit 620 outputs an optical control signal on thecontrol line 620-1 to drive the first control switch 621 (i.e., maintainswitch 621 in an “on” state), while the second control switch 622 ismaintained in an off state. On the other hand, when the voltage levelexceeds the predetermined trigger level trigger level, V_(TRIG), theswitch control circuit 620 outputs an optical control signal on thecontrol line 620-2 to drive the second control switch 622 (i.e.,maintain the second control switch 622 in an “on” state), while thefirst control switch 621 is maintained in an off state. In someembodiments, the switch control circuit 620 is configured such that theoptical drive control signal outputs 620-1 and 620-2 do not overlap,thereby providing a “break before make” switch characteristic, whichavoids discharging the capacitor 613 prematurely.

FIG. 6E is a schematic circuit diagram of a solid-state bidirectionalswitch 600-4 that can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure. The solid-statebidirectional switch 600-4 is similar in circuit configuration to thesolid-state bidirectional switch 600-1 of FIG. 6A, except that thesolid-state bidirectional switch 600-4 comprises a capacitor 613 that isconnected in parallel with the Zener diode 608, and wherein the secondbiasing branch comprising the second resistor 604 and the secondrectifier diode 606 is connected to the line neural 112 of the AC mains110, as opposed to being connected to the drain terminal D of the secondMOSFET switch 602.

The configuration of the solid-state bidirectional switch 600-4 avoidsthe clamping action that occurs for the configuration of FIG. 6A andallows the Zener diode 608 to reach its Zener voltage, V_(Z), when thesource terminal S of the second MOSFET switch 602 falls to −V_(z). Thiscauses the gate-to-source voltage of second MOSFET switch 602 to beV_(Z) which can be significantly larger than V_(T), which results in arelatively small thereby exhibiting a small drain-source resistancevalue (R_(DS)) and decreasing power dissipation. Furthermore, theboosted gate-to-source bias is stored on the intrinsic gate-to-sourcecapacitances of the MOSFET switches 601 and 602 and the capacitor 613,and is maintained during the subsequent positive half-cycle of thesupply voltage waveform of the AC mains 110. Thus, both MOSFET switches601 and 602 remain in minimum R_(DS) configurations until the switch 607is closed.

The first resistor 603 and the first rectifier diode 605 (bias branchelements) are maintained to improve the initial turn-on characteristicsduring a positive half-cycle, and the additional capacitor 613 inparallel with the intrinsic gate-to-source capacitances of MOSFETswitches 601 and 602 allows the storage of the boosted gate-to-sourcebias voltage to be more robust. When the solid-state bidirectionalswitch 600-4 is utilized in a phase-control mode, the switch 607 isclosed for a predetermined period during each cycle of the supplyvoltage waveform of the AC mains 110. Since the capacitor 613 isdischarged through the switch 607 while the switch 607 is closed, thegate-to-source bias required to turn on the MOSFET switches 601 and 602must be re-established during each cycle. This results in the firstMOSFET switch 601 operating in a suboptimal mode if the switch 607 opensduring the positive half cycle of the voltage waveform of the AC mains110 since the boost provided during the negative half cycle is resetwhen the switch 607 is closed.

FIG. 6F is a schematic circuit diagram of a solid-state bidirectionalswitch 600-5 that can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure. The solid-statebidirectional switch 600-5 is similar in circuit configuration to thesolid-state bidirectional switch 600-4 of FIG. 6E, except that thesolid-state bidirectional switch 600-5 implements a SPDT switch 632 inplace of the SPST switch 607, and wherein the gate terminals of thefirst and second MOSFET switches 601 and 602 are directly connected tothe input of the SPDT switch 632. The SPDT switch 632 is controlled by aswitch control circuit 630 which is coupled to the SPDT switch 632 by acontrol line 630-1. In some embodiments, the switch control circuit 630comprises an embodiment of the switch control circuitry 308 shown inFIGS. 3A and 3B. The switch control circuit 630 operates the SPDT switch632 to selectively connect the gate terminals of the MOSFET switches 601and 602 to either (i) the commonly connected source terminals S of theMOSFET switches 601 and 602 (“position 1”) or (ii) to the Zener diodebias circuit comprising the resistors 603 and 604, the rectifier diodes605 and 606, and the capacitor 613 (“position 2”).

More specifically, in this circuit configuration, activating the switch632 into position 1 causes the MOSFET switches 601 and 602 to turn “off”by disconnecting the gate terminals of the MOSFET switches 601 and 602from the Zener diode bias circuit and shorting out V_(GS) of the firstand second MOSFET switches 601 and 602 This allows the capacitor 613 tocharge to the Zener voltage of the Zener diode 608 until the capacitor613 is either discharged through the external circuitry or until theswitch 632 is placed into position 2, resulting in re-application of thestored Zener voltage to the gate terminals and the subsequent refreshingof the gate-to-source bias voltage during a negative half-cycle. In someembodiments, once charged, the capacitor 613 will never fully dischargeno matter the phase or the position of the switch 632 as long as thevalues of the resistors 603 and 604 and the capacitor 613 are selectedproperly, until AC power is removed.

FIG. 6G is a schematic circuit diagram of a solid-state bidirectionalswitch 600-6 that can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure. The solid-statebidirectional switch 600-6 is similar in circuit configuration to thesolid-state bidirectional switch 600-5 of FIG. 6F, wherein the SPDTswitch 632 (in FIG. 6F) is implemented using first and second controlswitches 641 and 642 that are controlled by a switch control circuit640. The switch control circuit 640 comprises a first control line 640-1that is coupled to the first control switch 641, and a second controlline 640-2 that is coupled to the second control switch 642. In someembodiments, the first and second control switches 641 and 642 comprisephototransistors (e.g., optical bipolar junction transistors).

The switch control circuit 640 is configured to synchronize the opticalcontrol signal outputs 640-1 and 640-2 to the supply voltage waveform ofthe AC mains 110. The switch control circuit 640 monitors the voltagelevel of the supply voltage waveform on the line hot path 111. While thevoltage level remains below a predetermined trigger level trigger level,V_(TRIG), the switch control circuit 640 outputs an optical controlsignal on the control line 640-1 to drive the first control switch 641(i.e., maintain switch 641 in an “on” state), while the second controlswitch 642 is maintained in an off state. On the other hand, when thevoltage level exceeds the predetermined trigger level trigger level,V_(TRIG), the switch control circuit 640 outputs an optical controlsignal on the control line 640-2 to drive the second control switch 642(i.e., maintain the second control switch 642 in an “on” state), whilethe first control switch 641 is maintained in an off state. In someembodiments, the switch control circuit 640 is configured such that theoptical drive control signal outputs 640-1 and 640-2 do not overlap,thereby providing a “break before make” switch characteristic, whichavoids discharging the capacitor 613 prematurely. The time constant forthe switch control allows for the rapid switching of the optical drivesignal outputs 640-1 and 640-2 in synchronism with the supply voltagewaveform of the AC mains 110 through external control circuitry (notshown) to provide phase control of the applied AC waveform, as is usedin dimmer applications.

FIG. 6H is a schematic circuit diagram of a solid-state bidirectionalswitch 600-7 that can be implemented in an intelligent circuit breaker,according to another embodiment of the disclosure. The solid-statebidirectional switch 600-7 is similar in circuit configuration to thesolid-state bidirectional switch 600-6 of FIG. 6G, except that thesolid-state bidirectional switch 600-7 comprises a current sensorcircuit 650 and a current sensing element 652. The current sensorcircuit 650 employs the current sensing element 652 to sense AC currentthat is delivered by the AC mains 110 to the load 120. In the exemplaryembodiment of FIG. 6H, the current sensing element 652 is coupled to anode between the serially connected first and second MOSFET switches 601and 602 (e.g., coupled to the node of the commonly connected sourceterminals S of the MOSFET switches 601 and 602). In some embodiments,the current sensing element 652 comprises a current transformer or aHall-Effect sensing element.

The current sensor circuit 650 is configured to generate and output acontrol signal to the switch control circuit 640 to selectively controlthe activation and deactivation of the control switches 641 and 642. Forexample, when the current sensor circuit 650 determines that there is nocurrent flow or excessive current flow in the hot line path between theline hot 111 and load hot 121, the current sensor circuit 650 willoutput a control signal to the switch control circuit 640 which causesthe switch control circuit 640 to (i) turn off the control switch 642 tothereby disconnect the first and second MOSFET switches 601 and 602 fromthe bias circuitry, and (ii) turn on the control switch 641 to therebydeactivate the first and second MOSFET switches 601 and 602 and placethe solid-state bidirectional switch 600-7 into a switched-off state.

In other exemplary embodiments, an intelligent circuit breaker canimplement the same or similar solid-state AC switching circuitry andtechniques as disclosed in any one of the following co-pendingapplications and issued patents: (1) U.S. patent application Ser. No.16/093,044, filed Oct. 11, 2018 (Pub. No.: US 2019/0207375), entitledSolid-State Line Disturbance Circuit Interrupter; (2) U.S. Pat. No.10,469,077, issued on Nov. 5, 2019, entitled Electronic Switch andDimmer; (3) International Patent Application No. PCT/US2018/059564,filed Nov. 7, 2018 (WO 2019/133110), entitled Electronic Switch andDimmer; (4) U.S. patent application Ser. No. 16/029,549, filed on Jul.7, 2018, entitled Solid-State Power Interrupter; (5) U.S. patentapplication Ser. No. 16/149,094, filed Oct. 1, 2018, entitled CircuitInterrupter with Optical Connection; and (6) U.S. patent applicationSer. No. 16/589,999, filed on Oct. 1, 2019, entitled Solid-State CircuitInterrupters, the disclosures of which are all fully incorporated hereinby reference.

FIGS. 7A and 7B schematically illustrate a switch control circuit forcontrolling a solid-state bidirectional switch, according to anembodiment of the disclosure. In particular, FIG. 7A is a schematicblock diagram of a switch control circuit that can be implemented in anintelligent circuit breaker for controlling a solid-state bidirectionalswitch, according to embodiment of the disclosure, and FIG. 7B is aschematic circuit diagram of the switch control circuit of FIG. 7A,according to embodiment of the disclosure. FIGS. 7A and 7B illustrate anexemplary embodiment of the switch control circuitry 308 for controllingthe solid-state bidirectional switch 304 in the exemplary embodiments ofFIGS. 3A and 3B.

FIG. 7A illustrates a solid-state bidirectional switch 700 comprisingfirst and second MOSFET switches 601 and 602 and respective body diodes601-1 and 602-1. The solid-state bidirectional switch is coupled to acontrol circuit 710 comprising a sense resistor 716, a short-circuitdetection and protection circuit 712, and a switch V_(GS) controller714. The sense resistor 716 is connected between the source terminals S(e.g., nodes N1 and N2) of the first and second MOSFET switches 601 and602. The short-circuit detection and protection circuit 712 isconfigured to detect a load-side short-circuit fault condition andoperate in conjunction with the switch V_(GS) controller 714 to providea fast disconnect of the solid-state bidirectional switch in response tothe detection of the short-circuit fault condition.

In particular, the short-circuit detection and protection circuit 712 iscoupled to nodes N1 and N2 and is configured to measure a burden voltageacross the sensor resistor 716 and determine when the burden voltageexceeds a pre-set value which is indicative of a short-circuit faultcondition. The short-circuit detection and protection circuit 712cooperates with the switch VGS controller 714 to rapidly shut-off thefirst and second MOSFET switches 601 and 602 when the burden voltageacross the sense resistor 716 exceeds the pre-set value. In someembodiment, the short-circuit detection and protection circuit 712 isconfigured to provide notification of the fault to a processor (e.g.,processor 220, FIGS. 3A and 3B).

As schematically illustrated in FIG. 7A, the switch V_(GS) controller714 is coupled to the gate terminals (e.g., node N3) of the first andsecond MOSFET switches 601 and 602. The switch VGS controller 714 isconfigured to control the activation and deactivation of the first andsecond MOSFET switches 601 and 602 during normal operation of thebidirectional switch (e.g., ON-state), and to deactivate both MOSFETswitches 601 and 602 in response to fault conditions. In addition, theswitch VGS controller 714 is configured to minimize leakage of the firstand second MOSFET devices 601 and 602 during on OFF state of thesolid-state bidirectional switch. In some embodiments, the switch VGScontroller 714 is configured to receive control signals (e.g., switchcontrol signal, leakage control signal) from a control processor (e.g.,processor 220, FIGS. 3A and 3B) to implement the switch V_(GS) controlfunctionality.

While FIG. 7A illustrates an exemplary embodiment in which the senseresistor 716 is connected between the source terminals S of the firstand second MOSFET switches 601 and 602, it is to be understood that thesense resistor 716 can be connected at other positions along a hot linepath between the line hot 111 and the load hot 121. In addition, thesense resistor 716 may also be utilized as an energy sensing element ofcurrent sensor and energy metering circuitry 240 of FIG. 3B such thatthe burden voltage across the sense resistor 716 is utilized by thedifferent sensing and control circuitry to implement the respectivefunctions.

FIG. 7B schematically illustrates a circuit diagram of the short-circuitdetection and protection circuit 712 according to an embodiment of thedisclosure. The sense resistor 716 is connected between nodes N1 and N2,wherein node N1 is coupled to the source terminal of the first MOSFETswitch 601 (denoted high-side switch) and wherein node N2 is coupled tothe source terminal of the second MOSFET switch 602 (denoted low-sideswitch), such as shown in FIG. 7A. The switch V_(GS) controller 714 isconnected to a node N4 of the short-circuit detection and protectioncircuit 712.

The short-circuit detection and protection circuit 712 comprises aplurality of bipolar junction transistors 720, 721, and 722, a N-typeMOSFET 724, a plurality of resistors 730, 731, 732, 733, 734, 735, and736, and a capacitor 740, all arranged and connected as shown in FIG.7B. The transistors 720, 721, and 722 are arranged to comprise a phasediscriminator featuring a fundamentally bidirectional support for ACcurrent. The short-circuit detection circuit 712 monitors the burdenvoltage across the sense resistor 716 (i.e., across nodes N1 and N2) andtrips the V_(GS) Control to the switches 601 and 602 when the burdenvoltage exceeds 0.7 Volts. More specifically, in this embodiment, theresistance value of the sense resistor 716 is chosen to generate abase-to-emitter (V_(BE)) which is sufficient to turn-on the bipolarjunction transistors 720 and 722 when the current flow through the senseresistor 716 meets or exceeds a predetermined maximum current value(e.g., trip current threshold). For higher trip currents, the resistancevalue of the sense resistor 716 decreases, whereas for lower tripcurrents, the resistance value of the sense resistor 716 increases. Forexample, for a trip current of about 200 amperes, the sense resistor 716would have a resistance value of about 30 milli-ohms.

One of ordinary skill in the art will understand that aground-referenced sensing circuit may be utilized, but that such circuitprovides an inferior, costly and complex solution requiring additionalcomponents including isolators. Also, the short-circuit trip current isadjustable by either changing the resistance value of the sensorresistor 716, or by adjusting its ability to influence the 0.7 Volt biaspoint with voltage dividers. In other embodiments, an additionalmechanism, such as a digital-to-analog converter (DAC), may be utilizedto influence and adjust the short-circuit current threshold inreal-time, thereby allowing the system to be programmable with regard tothe short-circuit current level. This programmability is particularlyuseful in extending the performance of the system to improve reactiontimes and reduce nuisance trips. As an example, a circuit breakeroperating under a heavy load may be far closer to a short-circuit tripthreshold than an unloaded breaker when both come to experience ashort-circuited load.

FIG. 8A is a high-level schematic illustration of an intelligent circuitbreaker according to another embodiment of the disclosure. Inparticular, FIG. 8A illustrates an intelligent circuit breaker 800 whichcomprises a solid-state bidirectional switch 801 and a load isolationswitch 802. The solid-state bidirectional switch 801 is seriallyconnected in the electrical path between a line input terminal(connected to the line hot 111) and a loud output terminal (connected tothe load hot 121) of the intelligent circuit breaker 800. The loadisolation switch 802 is connected across the load hot 121 and the loadneutral 122. It is to be understood that for ease of illustration anddiscussion, various components of the intelligent circuit breaker 800(e.g., processor, switch controllers, current sensors, voltage sensors,AC-to-DC converter circuitry, etc.) are not illustrated in FIG. 8A.

The intelligent circuit breaker 800 implements a control scheme toactivate the load isolation switch 802 to bypass the load 120 andthereby isolate (e.g., galvanically isolate) the load 120 from theintelligent circuit breaker 800 when the solid-state bidirectionalswitch 801 is in a switched-off state. This allows any leakage currentfrom the deactivated solid-state bidirectional switch 801 to flowthrough the isolation switch 802 to ground, and prevent such leakagecurrent from flowing to the load 120. The load isolation switch 802 isdeactivated when the solid-state bidirectional switch 801 is in aswitched-on state with the intelligent circuit breaker 800 supplyingpower to the load 120.

FIG. 8B is a high-level schematic illustration of an intelligent circuitbreaker which comprises isolation circuitry that is configured toisolate the intelligent circuit breaker from a load, according to anembodiment of the disclosure. More specifically, FIG. 8B illustrates anexemplary embodiment of the intelligent circuit breaker 800 of FIG. 8A,wherein the isolation switch 802 is implemented as part of an isolationcircuit 810 that is configured to isolate (e.g., dielectric isolation)the intelligent circuit breaker 800 from the load 120 when thesolid-state bidirectional switch 801 is in a switched-off state. Asnoted above, when the solid-state bidirectional switch 801 is in aswitched-off state, the solid-state bidirectional switch can generate asmall amount of leakage current. For example, even when the solid-statebidirectional switch 801 is biased to be in a completely switched-offstate, a small amount of leakage current (e.g., 200 uA) can flow throughthe solid-state switch 801 and generate a sizable voltage drop acrossthe load 120 when the load 120 comprises a high impedance load. Theisolation circuit 810 serves to shunt the unwanted leakage current fromthe load 120 when the solid-state bidirectional switch 801 isdeactivated.

The isolation circuit 810 comprises a controller 820, MOSFET devices 830and 840 and associated body diodes 830-1 and 840-1. In this exemplaryembodiment, the isolation switch 802 of FIG. 8A is implemented as asolid-state bidirectional switch comprising the MOSFET devices 830 and840. When the solid-state bidirectional switch 801 is placed into aswitched-off state, the controller 820 commands the MOSFET switches 830and 840 to turn on, which prevents any leakage current from thedeactivated solid-state bidirectional switch 801 from flowing to theload 120. The effect of bypassing or shunting leakage current away fromthe load 120 serves as an equivalent to a galvanic isolation techniquewhich can be implemented with an air-gap switch between the AC mains 110and the load 120. In this configuration, the isolation circuit 810provides dielectric isolation and serves as a pseudo air-gap. It is tobe appreciated that the isolation circuit 810 can be implemented inother exemplary embodiments of intelligent circuit breakers as discussedherein.

FIGS. 9A, 9B and 9C schematically illustrate an integrated currentsensor and energy metering circuit 900 that can be implemented in anintelligent circuit breaker, according to an embodiment of thedisclosure. In some embodiments, FIGS. 9A, 9B, and 9C illustrate anexemplary embodiment of the current sensor and energy metering circuit240 shown in FIGS. 2B and 3B. FIGS. 9A, 9B, and 9C illustrate differentcircuit blocks of the current sensor and energy metering circuit 900,wherein FIG. 9A is a schematic diagram of a power supply block 910 andcurrent sensor block 920, FIG. 9B is a schematic diagram of anover-current detection block 930, and FIG. 9C is a schematic diagram ofan energy metering block 980.

Referring to FIG. 9A, the power supply block 910 comprises an isolationDC-to-DC converter 911, a ferrite bead 912, capacitors 914 and 916, anda virtual ground (HGND) 918, all arranged and connected as shown. Theisolation DC-to-DC converter 911 is configured to convert a first DCsupply voltage VDC-A to a second DC supply voltage VDC-on-Hot andprovide isolation between the first and second DC supply voltages. Theferrite bead 912 is connected between the line hot 111 and a virtualground (HGND) 918. The capacitor 914 serves as a bypass capacitor thatis connected across the input terminals of the isolation DC-to-DCconverter 911 and, thus, connected between a VDC-A voltage rail andneutral ground (GND) 114. Similarly, the capacitor 916 serves as bypasscapacitor that is connected across the output terminals of the isolationDC-to-DC converter 911 and, thus, connected across a VDC-on-Hot voltagerail and the virtual ground HGND 918. The ferrite bead 912 andcapacitors 914 and 916 serve to filter high frequency noise from thesupply voltage rails.

In some embodiments, a first DC supply voltage VDC-A on the VDC-Avoltage rail comprises a DC supply voltage (e.g., 5V) generated by theAC-to-DC converter circuitry 210 (see FIGS. 2B and 3B), and theisolation DC-to-DC converter 911 provides a 1:1 conversion to generate asecond VDC-on-Hot supply voltage (e.g., 5V) which is applied toVDC-on-Hot voltage rail, which is connected to the line hot 111. In thisregard, the isolation DC-to-DC converter 911 generates the secondVDC-on-Hot voltage (e.g., 5V) that is applied to the hot line path toprovide a 5V DC offset on the hot line path, which is measured relativeto the virtual ground HGND 918, while the first DC supply voltage VDC-Ais measured relative to the neutral ground GND 114.

The current sensor block 920 comprises an isolation amplifier 921comprising a first block 921-1 and a second block 921-2, which aregalvanically isolated from each other using, e.g., optical couplingtechniques, capacitive coupling techniques, etc. The first block 921-1is powered by the VDC-on-Hot supply voltage generated by the powersupply block 910, and the second block 921-2 is powered by the VDC-Asupply voltage. The current sensor block 920 further comprises a currentsense resistor 922 and a low pass filter formed by resistors 923 and 924and capacitor 925 at the input of the isolation amplifier 921. A bypasscapacitor 926 is connected between the power supply rail VDC-A andground 114.

As shown in FIG. 9A, in some embodiments, the sense resistor 922 isserially connected in the electrical path between the line hot 111 andan AC switch. The sense resistor 922 generates an AC voltage (referredto herein as burden voltage (V_(B)) or sense voltage (V_(Sense)) acrossa first node N1 (referred to as line side node) and a second node N2(referred to as load side node) based on an AC load current that flowsthrough the sense resistor 922 in the hot line path. In someembodiments, the sense resistor 922 comprises a high-power resistor thathas a relatively low resistance value which can generate a sufficientsense voltage across the sense resistor 922 for purposes of measurement,while not consuming a large amount of energy. For example, in someembodiments, the sense resistor 922 comprises a resistance value ofabout 1 milli-Ohm.

In operation, the current sense resistor 922 generates a burden voltageV_(B) in proportion to the load current flowing on the hot line path.The burden voltage V_(B) is determined as: V_(B)=I_(L)×R_(S), whereI_(L) denotes the load current and R_(S) denotes the resistance value ofthe sense resistor 922. The first block 921-1 of the isolation amplifier921 amplifies and samples the voltage level of the burden voltage V_(B)across the sense resistor 922, and transmits (e.g., optically,capacitively, etc.) the sampled voltage information to the second block921-2 through the isolation barrier. In this circuit configuration, thebiasing of the first block 921-1 of the isolation amplifier 921 usingVDC-on-Hot and the virtual HGND 918 allows the first block 921-1 of theisolation amplifier 921 to measure the voltage across the sense resistor922 (which is serially connected in the hot line path) relative to thevirtual ground HGND 918. The isolation between the first and secondblocks 921-1 and 921-2 of the isolation amplifier 921 allows the secondblock 921-2 and the downstream circuit components to be biased usingVDC-A and the neutral ground GND 114.

The second block 921-2 of the isolation amplifier 921 utilizes thesampled voltage information provided from the first block 921-1 togenerate and output a differential signal comprising first and secondcurrent sense control signals (denoted Current_Sense(+) andCurrent_Sense(−)) with respect the neutral ground GND 114. In someembodiments, the differential output of the isolation amplifier 921 isimplemented as a differential signal having a DC offset (e.g., 1.3 Voffset) and a desired gain (e.g., gain of 8). The first and secondcurrent sense control signals (Current_Sense(+) and Current_Sense(−))are input to the over-current detection block 930 (FIG. 9B) and theenergy metering block 980 (FIG. 9C).

In some embodiments, as shown in FIG. 9A, the isolation amplifier 921 isconfigured to have an adjustable gain that can be controlled by aprocessor or controller of the intelligent circuit breaker. Inparticular, as shown in FIG. 9A, the second block 921-2 of the isolationamplifier 921 comprises a Gain Adjust control input that allows theprocessor or controller to adjust the gain of the isolation amplifier921 and thereby adjust the level of the over-current condition at whichthe intelligent circuit breaker will trip. In this configuration, theisolation amplifier 921 provides an element of gain to amplify arelatively small sense voltage that is generated across the senseresistor 922 (i.e., across node N1 and N2) as a result of current flowon the hot line path between the line hot 111 and the load hot 121. Assuch, the sense resistor 922 can have a relatively small resistancevalue (e.g., 1 milliohm) which generates a relatively small sensevoltage and minimizes power dissipation for normal circuit operation,but which is amplified by the isolation amplifier 921 to enableover-current detection using the small sense voltage. Moreover, theresistance value of the sense resistor 922 can remain fixed (e.g., 1milliohm) while the gain of the isolation amplifier 921 is adjusted asdesired to adjust the level of over-current detection.

In some embodiments, the processor or controller can be configured toadjust the gain of the amplifier 912 based on the temperature of theintelligent circuit breaker, as determined by a temperature sensor thatis integrated with or otherwise coupled to the intelligent circuitbreaker. For example, in instances where the temperature of theintelligent circuit breaker increases to a relatively high level (e.g.,115 degrees Celsius and above), the gain of the isolation amplifier 921can be adjusted (e.g., increased) to reduce the level of theover-current at which the intelligent circuit breaker trips.

Referring to FIG. 9B, the over-current detection block 930 comprises aunity-gain amplifier 931, and a two stage detection circuit 935comprising an RMS stage 935-1 and a comparator stage 935-2. Theunity-gain amplifier 931 has a non-inverting input connected to node N3between resistors 932 and 933. The resistors 932 and 933 are seriallyconnected between the differential outputs of the isolation amplifier921 of the current sensor block 920 (FIG. 9A). The unity-gain amplifier931 and resistors 932 and 933 serve as a level-shift input stage for theover-current detection block 930, wherein the resistors 932 and 933 areselected to have the same resistance value to address the DC offset(e.g., 1.3 V offset) of the differential output of the isolationamplifier 921. In this regard, the over-current detection block 930utilizes only one side of the current sensing differential output of theisolation amplifier 921 so effectively the input to the over-currentdetection block 930 is given by Vin_OCD=1.3V+Aa/2×I_(L)×R_(S), where Ais 8, wherein “a” denotes the peak amplitude of the AC waveform that isamplified by the isolation amplifier 921 of the current sensor block920.

The output of the unity-gain amplifier 931 is input to the RMS stage935-1. The RMS stage 935-1 comprises an active peak detection circuitwhich is configured to generate an output signal that represent an RMS(root mean square) value of Vin_OCD. The RMS stage 935-1 comprises afirst amplifier 940 and a second amplifier 950. The first and secondamplifiers 940 and 950 comprise respective non-inverting inputs that arecoupled to the output of the unity-gain amplifier 931 through resistors941 and 951, respectively. The first and second amplifiers 940 and 950comprise respective inverting inputs that are coupled to theCurrent_Sense(−) output of the current sensor block 920 throughresistors 942 and 943, respectively. The output of the first amplifier940 is coupled to an inverting input of the second amplifier 950 througha rectifier diode 946 and a resistor 952. The first amplifier 940comprises a first negative feedback loop comprising a rectifier diode945 and a second negative feedback loop comprising a resistor 944. Thesecond amplifier 950 comprises a negative feedback look comprising aparallel connected resistor 953 and capacitor 954.

The RMS stage 935-1 is configured to generate a RMS voltage which isgiven by V_(RMS)=1.3V−RMS(Aa/2×I_(L)×R_(S)) or1.3V−(0.707)×Aa/2×I_(L)×R_(S), assuming a sinusoidal wave. The RMSvoltage is generated at the output of the second amplifier 950, which iscoupled to the input of the second (comparator) stage 935-2. Thecomparator stage 935-2 comprises a comparator 960 having an invertinginput coupled to the output of the amplifier 950 to receive the RMSvoltage V_(RMS), and a non-inverting input which receives as input aCurrent_Threshold control signal. In some embodiments, theCurrent_Threshold control signal comprises a current that is generatedby a current DAC (digital-to-analog converter) in a control processor(e.g., processor 220, FIGS. 2B and 3B). The Current_Threshold controlsignal generates a current threshold voltage, V_(CT), across a resistor961 which is connected to the non-inverting input of the comparator 960.In some embodiments, a resolution of the DAC is 2.4 μA/bit and theresistor 961 has a resistance value of 4320Ω. This results in thecurrent threshold voltage V_(CT) having a resolution of 10.368 mV/bit atthe non-inverting input of the comparator 960. The relationship betweenthe DAC code and the Current_Threshold (CT) is given byD=(1.3V−(Aa/2×CT×R_(S))/(10.368 mV/bit) or D=(1.3V−16 mΩ×Ct)/(10.368mV/bit) where CT is in Amps RMS.

Since the RMS voltage V_(RMS) generated by the RMS stage 935-1 may havesome voltage ripple, the comparator stage 935-2 is implemented as atwo-stage comparator comprising the first comparator 960 and a secondcomparator 970. The comparator 960 compares V_(CT) with V_(RMS). If theV_(CT) with V_(RMS) signals are close to one another, the output of thefirst comparator 960 will dither with a duty cycle in relation to howmuch over or under current V_(RMS) represents. The first comparator 960has an output that is coupled to a non-inverting input of the secondcomparator 960 through a low pass filter formed by resistor 962 andcapacitor 963. The second comparator 970 comprises an inverting inputthat is connected to a voltage divider network comprising first andsecond resistors 971 and 972 that are serially connected between thesupply voltage VDC-A and ground GND 114. The voltage divider networkgenerates a reference voltage VREF that is applied to the invertinginput of the second comparator 970. The second comparator 970 generatesan Over_Current_Detection signal when the duty cycle of the firstcomparator 960 is greater than 50%.

The Over_Current_Detection signal is input to control circuitry todeactivate an AC switch of the circuit breaker to protect against theover-current fault condition. An exemplary control process which can beimplemented by a processor of an intelligent circuit breaker inconjunction with the current sensor circuitry 900 of FIGS. 9A and 9B formonitoring and detecting over-current fault conditions will be explainedin further detail below with reference to FIG. 11.

Referring now to FIG. 9C, the energy metering block 980 comprises anenergy metering circuit 981 and a passive bandpass filter comprisingresistors 982, 983 and 984 and capacitors 985, 986, and 987. The energymetering circuit 981 comprises a differential input that is coupled tothe differential output, Current_Sense(+) and Current_Sense(−), of theisolation amplifier 921 of the current sensor block 920 (FIG. 9A)through the passive bandpass filter. Effectively, the input voltageV_(CM) to the energy metering circuitry 981 is provided byV_(CM)=(Aa×I_(L)×R_(S))/A_(N) (where A_(N) denotes an attenuation of thebandpass filter), since the bandpass filter removes the DC offset (e.g.,1.3 V offset), attenuates the Current_Sense(+) and Current_Sense(−)signals, and highly attenuates unwanted high frequencies. From theperspective of energy metering software, a useful constant is thecurrent-to-voltage ratio, K_(S)=Aa×R_(S)=0.032Ω (assuming that Aa=8 andR_(S)=0.004Ω), wherein 1/K_(S)=A_(N)/(Aa*R_(S))=656.25 Amp/Volt.

It is to be understood that the various resistance and capacitancevalues of the circuit components in FIGS. 9A, 9B, and 9C can varydepending on the application. To provide some context, the followingnon-limiting examples of resistance and capacitance values can beimplemented in the circuitry of FIGS. 9A, 9B, and 9C. For example, inFIG. 9A, the values of the resistors 922, 923 and 924 and the capacitor925 are selected to provide desired input signal filtering.

Furthermore, in some embodiments, the resistance values and capacitorvalues in FIG. 9B are as follows. The resistors 932 and 933 have aresistance value of 5.9K. The resistor 941 has a resistance value of4.7K. The resistors 942, 943 and 944 have a resistance value of 10K. Theresistor 951 has a resistance value of 2.7K. The resistor 952 has aresistance value of 4.99K. The resistor 953 has a resistance value of11K. The capacitor 954 has a capacitance value of 2.2 uF. The resistor961 has a resistance value of 4.3K. The resistor 962 has a resistancevalue of 22K. The capacitor 963 has a capacitance value of 0.47 uF. Theresistors 971 and 972 have a resistance value of 22K.

Moreover, in some embodiments, the resistance values and capacitorvalues in FIG. 9C are as follows. The resistors 982 and 983 have aresistance value of 4.7K. The resistor 984 has a resistance value of 470Ohms. The capacitors 985 and 986 have capacitance values of 10 uF. Thecapacitor 987 has a capacitance value of 10 nF. In some embodiments, theenergy metering circuit 981 comprises an application-specific integratedcircuit (ASIC) which is specifically designed to measure power andenergy in a power line system and process instantaneous voltage andcurrent waveforms to compute RMS values of voltage and currents, active,reactive and apparent power and energies. In other embodiments, theenergy metering circuit 981 comprises an “off-the-shelf”application-specific standard product (ASSP) chip that implements thedesired energy metering functionalities.

The energy metering circuit 981 generates and outputs energy meteringdata to the processor 220 of the intelligent circuit breaker (e.g.,FIGS. 2B and 3B), and the processor 220 stores and analyzes the energymetering data to determine energy usage of the load on a branch circuitthat is protected by the intelligent circuit breaker. The processor 220can provide energy usage information to a remote computing node ordevice via a wireless or wired network connection. This configurationallows remote energy monitoring and notification of energy usage andthereby improves energy awareness for various applications.

By way of example, a plurality of energy-aware intelligent circuitbreakers can be configured to report real-time and accumulated energyusage from a plurality of branch circuits within a given residence orbuilding. The energy-aware intelligent circuit breakers within the givenresidence or building can provide accumulated energy usage informationwhich a property owner can utilize to validate or otherwise correlatethe energy usage of the given residence or building as reported by autility company. In addition, in multi-dwelling or multi-unitproperties, such as strip malls, the intelligent energy metering usingenergy-aware intelligent circuit breakers allows a property owner toindividually bill tenants without the need for multiple utility meters.As another example, intelligent energy metering by intelligent circuitbreakers is also useful with renters or Airbnb rentals to prevent orreport unnecessary waste of energy such as a renter sleeping with thewindow open on a cold night with an electric heater continuouslyoperating at full power, or an AC unit on a maximum cooling settingwhile the renter sleeps beneath heavy covers on a warm night.

As another example, intelligent energy metering by intelligent circuitbreakers provides a way of determining possible energy theft or unusualand unexpected energy consumption and can also reveal defective ormalfunctioning utility meters. In other applications, intelligentenergy-aware circuit breakers are also capable of sendingalerts/notifications when electrical usage exceeds a settable “normallevel” for devices on a branch or an aggregation of devices andbranches. Furthermore, intelligent energy-aware circuit breakers arealso useful to utility companies as they search for loads that can bedisabled or power-reduced during peak load periods. For example, in someembodiments, an intelligent circuit breaker can implement the loadprofiling techniques as disclosed in U.S. patent application Ser. No.16/682,627, filed on Nov. 13, 2019, entitled Managing Power forResidential and Commercial Networks, the disclosure of which isincorporated by reference herein in its entirety. These same smartdevices, as disclosed, are capable of providing valuable outageinformation in the moments during the collapse of utility power andduring the restoration of circuits. The timing of outages can helppin-point the location of downed or damaged power lines, assist inestimating the number of points of damage, and help generate moreaccurate utility restoration times. In other applications, intelligentenergy-aware circuit breakers are also capable of measuring, diagnosing,and controlling the increasingly improperly synchronized bi-directionalenergy commonly experienced with renewable energy sources and electricvehicles connected to building infrastructures and utility energysupplies.

FIG. 10 is a flow diagram of a method for controlling a switch of anintelligent circuit breaker in response to detection of faultconditions, according to an embodiment of the disclosure. Forillustrative purposes, the exemplary process flow of FIG. 10 will bediscussed in the context of controlling a solid-state bidirectionalswitch of an intelligent circuit breaker, although the same or similarprocess flow may be implemented to control an electromagnetic switch(e.g., switch 302, FIGS. 3A and 3B) of an intelligent circuit breaker.Upon application of utility supply power, control logic of theintelligent circuit breaker assumes control of a solid-statebidirectional switch (block 1000). Initially, the control logic willplace the solid-state bidirectional switch into an open state (orswitched-off state) (block 1001), and proceed to determine when it isappropriate to place the solid-state bidirectional switch into a closedstate (or switched-on state) (block 1002).

For example, the control logic may determine that is appropriate toclose the solid-state bidirectional switch based on (i) the manualcircuit breaker switch position (e.g., manual switched is closed), (ii)the switch condition at the time of loss of utility power (e.g., switchwas closed at time of loss of power), (iii) commands received from alocal processor or commands received wirelessly from a remote node, (iv)end-of-life disablement conditions, etc. Once the solid-statebidirectional switch is in a closed state (block 1003), the controllogic will proceed to monitor for the occurrence of an event that isdeemed to require placing the solid-state bidirectional switch into anopen state, i.e., switched-off state (block 1004).

For example, the occurrence of a fault event such as a current overloadevent (block 1005) or a short-circuit event (block 1006) would triggerthe deactivation (i.e., switched-off state) of the solid-statebidirectional switch. For example, as noted above, in some embodiments,a current overload event can be determined by a processor analyzingreal-time current sensor data obtained using a current sensor configuredto detect line current. In other embodiments, the intelligent circuitbreaker comprises a current sensor that comprises current overloaddetection circuitry (e.g., FIGS. 9A and 9B) which is configured todetect a current overload event, and to generate a current overloaddetection signal that triggers the opening of the solid-statebidirectional switch.

In other embodiments, detecting the opening of the manual circuitbreaker switch is deemed an event that would trigger the opening of thesolid-state bidirectional switch (block 1007). As noted above, in thisinstance, the opening of the solid-state bidirectional switch before orconcurrently with the manual switch opening event would serve toeliminate or minimize the occurrence of electrical arcing between thecontacts of the electromechanical or electromagnetic switch of theintelligent circuit breaker. The occurrence of arcing causes degradationof the metal contacts of a circuit breaker and is a safety hazard insituations where flammable gasses may be present. In this regard, theability to eliminate arcs during fault events or manual lever action areexamples of how intelligent circuit breakers disclosed herein extendingthe safety of circuit breakers beyond simply protecting the downstreamcircuit wiring from thermal damage. Moreover, as noted above, theimplementation of a solid-state bidirectional switch with a fastdisconnect response time prevents the flow of dangerous current levelsthat could cause arcing in downstream wiring and loads.

In other embodiments, a remote switch open command event would triggerthe opening of the solid-state bidirectional switch (block 1008). Asnoted above, the implementation of wireless transceiver within anintelligent circuit breaker enables wireless communication to remotelydisconnect a branch circuit and load(s) protected by the intelligentcircuit breaker. For example, the remote switch open command capabilityallows emergency service personnel to power-down part or all of astructure during a reported gas leak or flood event. The implementationof the wireless transceiver through a secure Internet Protocol (IP)address and IP network allows a remote command to be issued to thecontrol logic of the intelligent circuit breaker to switch off thesolid-state bidirectional switch and, in effect, trip the intelligentcircuit breaker.

In other embodiments, a sensor data trip event would trigger the openingof the solid-state bidirectional switch (block 1009). As noted above,the implementation of various sensors and a processor with control logicenables tripping of an intelligent circuit breaker in response tovarious sensed conditions. For example, in addition to current andvoltage sensors, an intelligent circuit breaker can include other typesof sensors such as temperature sensors, humidity sensors, etc. Theability to acquire sensor data combined with the implementation ofcontrol algorithms that are able to process the acquired sensor data andto predict for dangerous and problematic events and issue wirelessalerts/notifications extends the safety capabilities of intelligentcircuit breakers as disclosed herein.

For example, by acquiring and processing sensor data, an intelligentcircuit breaker can be configured to initiate the opening of thesolid-state switch just prior to a potential fault condition of a loadby predicting an imminent failure of the load such as a spa pump,heater, or a compressor of a central air conditioning system, etc. Insome embodiments, an intelligent circuit breaker can implement thepredictive analytic techniques as disclosed in U.S. patent applicationSer. No. 15/980,311, filed May 15, 2018, and entitled PredictiveAnalytics System, the disclosure of which is incorporated by referenceherein in its entirety. Moreover, the ability of an intelligent circuitbreaker to identifying a load type (e.g., a spa pump), can be veryhelpful in analyzing potentially unsafe conditions. In some embodiments,an intelligent circuit breaker can implement the circuit loadcharacterization techniques as disclosed in U.S. patent application Ser.No. 16/340,474, filed on Apr. 9, 2019 (Pub. No.: US 2019/0245457),entitled Load Identifying AC Power Supply with Controls and Methods, thedisclosure of which is incorporated by reference herein in its entirety.Furthermore, the wireless communications ability of an intelligentcircuit breaker allows enhanced support for new types of load profiles,such as a new type of refrigeration motor, and unusual alternativeenergy feeds through automatic software, firmware, and algorithm updatesfrom a remote site.

As another example, the sensors, when intelligently connected todownstream electrical devices, can detect unsafe conditions at specificreceptacles or loads. A 20 Amp circuit breaker typically feeds numerousdownstream receptacles. Each of these receptacles may be 15 Amp rateddevices with the assumption that a 20 Amp load is shared across multiplereceptacles. Sensors in the circuit breaker may alert a particular smartreceptacle, smart load, or property owner to an unsafe condition, suchas overloaded and daisy-chained power strips, or too many strings ofholiday lights on a single receptacle. As discussed in further detailbelow in conjunction with FIG. 15, an intelligent circuit breaker couldissue a wireless alert/notification, or direct the receptacle todisconnect, or simply trip the breaker itself until the situation isrectified and reset.

In another embodiment, the ability of an intelligent circuit breaker tocharacterize load types, whether through algorithms or with dataprovided by the property owner, allows the intelligent circuit breakerto detect or otherwise monitor for potential degradation in theperformance of a given load type. This is particularly useful, forexample, in providing information for preventative maintenance on arefrigeration unit prior to failure and any resulting spoilage andnumerous other types of appliances or loads. In this regard, anintelligent circuit breaker can be configured to identify and profilemany types of loads and compare the real-time operating profile of agiven load with a nominal operation profile of the given load. Appliancemanufacturers will benefit greatly from the big data gatheringassociated with energy usage profiling, communication, and analysis.

In other embodiments, an intelligent circuit breaker can be paired witha smart receptacle to detect an overload condition of the smartreceptacle with an ability to wirelessly communicate before re-supplyingpower to its load, may trip a branch circuit given a dangerous faultcondition, and re-apply power automatically by wirelessly directing theoffending smart receptacle to remain in a load-disconnected state afterpower is reapplied to the branch circuit by the intelligent circuitbreaker. This enables the intelligent circuit breaker to re-energize andcontinue servicing power to all the other loads on the given branch,details of which will be discussed below in conjunction with the flowdiagram of FIG. 15. Further, an intelligent circuit breaker, when pairedwith smart receptacles with more than one individual branch feed orphase and a mechanism to switch between them, is able to direct smartreceptacles to switch branch circuits in an effort to balance the loadand more economically make use of phase balancing.

In other embodiments, an intelligent circuit breaker may comprise, orotherwise be connected to remote sensors, such as temperature, humidity,gas, smoke/fire, and water sensors. The intelligent circuit breaker canmonitor environmental conditions using such sensors and react to unsafeconditions by disconnecting power from branch circuits in conditionswhere unsafe water levels may lead to electrocution or fire, or unsafetemperatures may lead to device failures within the circuit breakerpanel. By way of specific example, a humidity sensor can be disposedwithin an intelligent circuit breaker, or within a breaker distributionpanel, or within a wall, and be used to detect a roof or plumbing leakthat may adversely impact the safety of the entire electrical system.The intelligent circuit breakers are also able to issue wirelessalerts/notifications prior to or immediately after a fault event. Eachof these examples may also include a wireless notification to localemergency services and, or, the local utility companies.

In other embodiments, intelligent circuit breakers comprising arc-faultand/or ground-fault sensors are also able to safely shut down branchcircuits in unsafe conditions. The intelligent circuit breakers canissue wireless alerts/notifications prior to or immediately after sucharc-fault or ground-fault events. Each of these examples may alsoinclude a wireless notification to local emergency services and, or, thelocal utility companies.

In other embodiments, additional information derived from externalsensors or data available through wireless communications may also beutilized to cause a notification/alert or a trip event.

FIG. 11 is a state diagram that illustrates a control process which isimplemented by an intelligent circuit breaker to detect and protectagainst fault conditions, according to an embodiment of the disclosure.In particular, FIG. 11 illustrates a fault detection state graph thatillustrates a state machine which is implemented by a processor of anintelligent circuit breaker (e.g., processor 220 of intelligent circuitbreakers 2B and 3B) to detect over-current fault conditions. In someembodiments, the processor 220 comprises a current digital to analogconverter (current DAC) to generate programmable reference current(e.g., Current Threshold, FIG. 9B) and a general-purpose input/output(GPIO) digital signal pin to receive an over-current detection signalgenerated by a current sensor (e.g., Over_Current_Detection signalgenerated by the over-voltage comparator 935-2 of the over-currentdetection block 930 of the current sensor 900, FIG. 9B).

In some embodiments, the processor 220 implements a 1 KHz state machineto detect over-current fault conditions, wherein the state machinecomprises the following states: (i) Stopped; (ii) Reset; (iii)Over-Current Detection (S0); (iv) Slow Blow Ramp (S1); (v) TailDetection (S2); and (vi) Tripped. In addition, in some embodiments, thestate machine implements the following programmable parameters: (i) OCT,which denotes an Over-Current Threshold (output during S0 and S2); (ii)ITT, which denotes an Instantaneous Trip Threshold (the start of the S1Ramp); (iii) SBRT, which denotes a Slow Blow Ramp Time (the duration ofS2); and (iv) TT, which denotes a Tail Time (S2 Duration).

The states are defined as follows. The Stopped state is used when a tripor fault condition has been detected to stop the current detection untilset to the Reset state by a command. The Reset state is the initialstate used to start the state machine, it initializes the DAC output tothe over-current threshold detection circuitry and sets the statemachine to the S0 state. In the S0 state, the current DAC is programmedto output the voltage that represents the desired over-current threshold(OCT) that is input into the comparator stage of the over-currentdetection block 930 of the current sensor 900, FIG. 9B. This is thesteady state until the current rises higher than the output threshold asmeasured at the comparator circuit, at which point the comparator willoutput a logic level “1” as an Over_Current_Detection signal, which willbe detected by the over-current state machine. At that time, the DAC isprogrammed to the instantaneous trip threshold and will setup the rampduration and the length and duration of each step needed for the stateS1, and the state machine transitions to the S1 state.

During the S1 state, anytime the comparator output transitions to logic“1” is considered a trip condition and the state machine willimmediately move to the Tripped state. During the S1 state, the SlowBlow Ramp will be executed, with the DAC being adjusted in steps as timeelapses from the Instantaneous Trip Threshold back to the Over-CurrentThreshold. If the ramp completes without the comparator indicating atrip condition, then the state machine will be moved to the S2 state.While the ramp does not have to be linear as shown in FIG. 11, the rampcan be weighted or non-linear in any way desired to achieve the desiredeffect, e.g. the heating characteristics of the wiring being protected.In some embodiments, the S1 ramp could be perturbed (via softwarecontrol) to compensate for an increased temperature of the intelligentcircuit breaker.

During the S2 state, anytime the comparator output transitions to logic“1” will be considered a trip condition and the state machine willimmediately move to the Tripped state. During the S2 state, the DAC willoutput the over-current threshold (the same as in state S0) for theprogrammed period of time, giving the state machine an opportunity todetect a condition where the current is steady and exactly at theover-current threshold reference level, instead of continuously cyclingthrough the over-current states without actually declaring the tripcondition. At the end of the S2 period, the state machine is set to theReset state (which sets the DAC output to the over-current threshold andsets the state to S0).

When the Tripped state is entered, as a result of an over-currentdetection in either the S1 or S2 states, the AC Switch Off action isinitiated, which will result in the AC switch control lines beingswitched to the off state on or before the next zero cross functionexecution.

In another embodiment, a “wire heating” process is implemented byvarying the S0 output current based on how many times high current tripshave occurred without exceeding the over-current detection. The processcould implement a secondary state machine that is configured to vary (indurations of seconds or minutes) the S0 level, the instantaneous triplevels, and the slope of the slow blow ramp accordingly.

FIG. 12 schematically illustrates an intelligent power distribution andmonitoring system 1200 which utilizes intelligent circuit breakersaccording to an embodiment of the disclosure. The system 1200 comprisesa circuit breaker distribution panel 1210, a wired and/or wirelesscommunications network 1220, one or more intelligent load devices 1230,one or more user computing devices 1240, and an Internet of Things (IoT)computing platform 1250. The circuit breaker distribution panel 1210comprises a front panel 1211 and cover 1212 which is opened to access amain circuit breaker 1213 and a plurality of branch circuit breakers1214 that protect branch circuits in a given dwelling or building, and abreaker and load status display module 1215.

The configuration of the circuit breaker distribution panel 1210 willvary depending on the type of electrical service that is provided. Forexample, residential electric service in the United States (120/240 VAC)comprises a single-phase service comprising two hot voltage lines andone neutral line, wherein both line voltages are derived from a singlephase of a distribution transformer with a center tapped neutral and are180° out of phase with each other. In this type of electrical service,two hot line service wires that feed the circuit breaker panel 1210 areconnected to the main circuit breaker 1213, and the main circuit breaker1213 is connected to two hot bus bars within the circuit breaker panel1210. In addition, an incoming neutral line service wire is connected toa neutral bus bar in the circuit breaker panel 1210, and the neutral busbar is coupled to a separate grounding bus bar in the circuit breakerpanel 1210.

The two hot line service wires feeding the main circuit breaker 1213each provide 120V from, e.g., an electric meter, and feed the two hotbus bars in the circuit breaker panel 1210 through the main circuitbreaker 1213 (when the main circuit breaker 1213 is switched on). Thebranch circuit breakers 1214 have line input terminals that connect toone or both of the hot bus bars to provide power to the circuits (e.g.,a single-pole circuit breaker has one input line terminal which connectsto one hot bus bar to provide 120V to a branch circuit, while adouble-pole circuit breaker comprises two input line terminals whichconnect to both hot bus bars to provides 240V to a branch circuit). Inaccordance with embodiments of the disclosure, some or all of the maincircuit breaker 1213 and the branch circuit breakers 1214 compriseintelligent circuit breakers that are implemented using intelligentcircuitry and functionalities as discussed herein. In this instance, theintelligent circuit breakers 1213 and 1214 would have a connection tothe neutral line, e.g., a wire that connects the ground plane for thesolid-state circuitry to the neutral bus bar in the circuit breakerpanel 1210.

The intelligent load devices 1230 may comprise various types ofintelligent devices such as intelligent electrical receptacles orintelligent energy consuming load devices, including, but not limitedto, switches, power outlets, light bulbs, appliances, heating systems,ventilation systems, air conditioning systems, appliances, communicationsystems, entertainment systems, home security devices, etc., and othertypes of smart electrical and electronic devices and systems that areutilized in residential, commercial or industrial buildings.

In the context of IoT computing, the intelligent circuit breakers 1213and 1214 and the intelligent load devices 1230 comprise smart IoTdevices that operate and communicate within a IoT device network and areconfigured to support an IoT applications for a given applicationdomain. The IoT devices (e.g., 1213, 1214 and 1230) generate data whichis uploaded to the IoT cloud computing platform 1250 over thecommunications network 1220 for data processing, data storage and datamanagement by the cloud computing platform 1220. In addition, the IoTdevices can access and download data from the IoT cloud computingplatform 1250 over the communications network 1220. Moreover, dependingon the types of devices and network configuration, some or all of theIoT devices (e.g., 1213, 1214 and 1230) are configured for peer-to-peercommunication within the IoT device network. The IoT devices areconfigured to form a network (e.g., mesh network) throughself-organization using known methods.

The user computing devices 1240 comprise one of various types ofcomputing devices such as a desktop computer, a laptop computer, aserver, a smart phone, an electronic tablet, etc., which allows a useror administrator to access the IoT cloud computing platform 1250 and theintelligent devices 1213, 1214, and 1230 over the communications network1220. The user computing devices 1240 can host a client-side IoTapplication that is utilized to configure and manage the networkintelligent devices 1213, 1214, and 1230, either directly or through theIoT cloud computing platform 1250.

While the communications network 1220 is generically depicted in FIG. 1,it is to be understood that the communications network 1220 may compriseany combination of known wired and/or wireless communication networkssuch as, a global computer network (e.g., the Internet), a wide areanetwork (WAN), a local area network (LAN), a satellite network, atelephone or cable network, a cellular network, a wireless network suchas Wi-Fi or WiMAX, Bluetooth, or various portions or combinations ofthese and other types of networks. The term “communications network” isbroadly construed so as to encompass a wide variety of different networkarrangements, including combinations of multiple networks possibly ofdifferent types. In this regard, in some embodiments, the communicationsnetwork 1220 comprises combinations of multiple different types ofcommunications networks each comprising network devices configured tocommunicate using Internet Protocol (IP) or other related communicationprotocols. The communications network 1120 comprises intermediate points(such as routers, switches, etc.) and other elements (e.g., gateways)that form a network backbone to establish communication paths and enablecommunication between network endpoints.

In the context of IoT computing, the communications network 1220comprises an IoT device network, wherein the intelligent circuitbreakers 1213 and 1214 and the intelligent load devices 1230 (and otherwireless/wired sensors such as humidity sensors, temperature sensors,etc.) comprise smart IoT devices that operate and communicate within theIoT device network and are configured to support an IoT application fora given application domain (e.g., controlling and managing intelligentcircuit breakers and smart electrical devices within a given dwelling orbuilding, collecting and analyzing energy usage information for thegiven dwelling or building, etc.).

The IoT devices (e.g., 1213, 1214 and 1230) generate data which isuploaded to the IoT cloud computing platform 1250 over thecommunications network 1220 for data processing, data storage and datamanagement by the cloud computing platform 1220. In addition, the IoTdevices can access and download data from the IoT cloud computingplatform 1250 over the communications network 1220. The IoT cloudcomputing platform 1250 manages and processes IoT data received from thevarious IoT devices 1213, 1214, and 1230. In some embodiments, the IoTcloud computing platform 1250 performs data processing, data storage,and data management functions and support one or more IoT networkapplications and/or other types of high performance computingapplications such as deep learning applications, machine learning, bigdata analytics, or other types of high performance computingapplications that are useful for supporting a home or buildingautomation system which comprises network of smart electrical devicesthat can be monitored and controlled using techniques as disclosedherein.

Moreover, depending on the types of devices and network configuration,some or all of the IoT devices (e.g., 1213, 1214 and 1230) areconfigured for peer-to-peer communication within the IoT device network.The IoT devices are configured to form a network (e.g., mesh network)through self-organization using known methods. In some embodiments,wireless communication between the IoT devices (e.g., 1213, 1214 and1230) and wireless communication between the user computing devices 1240and the IoT devices (e.g., 1213, 1214, and 1230) can be implementedthrough radio frequency communication protocols and systems such asBluetooth®, near-field communication, Wi-Fi devices, Zigbee®, and otherproprietary and non-proprietary protocols. In addition, various sensorssuch as temperature, humidity, motion and sound sensors may be includedas part of the IoT device network to provide environmental informationthat is used by the intelligent circuit breakers 1213 and 1214 toprotect against potential electrical hazards that may result fromadverse environmental conditions.

In some embodiments, the breaker and load status display module 1215comprises a master processor that communicates with the processors ofthe intelligent circuit breakers 1213 and 1214 and the intelligent loaddevices 1230 to obtain, process, and display operating status data ofsuch devices. The master processor is configured to display analog ordigital data received from various intelligent devices and sensors andprovide status of the breakers (e.g., tripped, overload, etc.) andactivate alarms/notifications when sensor readings are outside ofpre-selected limits. The alarms include a visual display on the userinterface of the faceplate, an audible sound from the audio outputdevice, a communication signal sent through the electronic communicationmodule and signal sent to a light or audio alarm. In some embodiments,the user computing devices 1240 can access the breaker/load statusdisplay module 1215 to obtain status information regarding the IoTdevices and issue commands to perform certain functions (e.g., trip anintelligent breaker, reset and intelligent breaker, etc.). In someembodiments, the system 1200 of FIG. 12 implements home/buildingautomation and controls systems and methods as disclosed inInternational Application No. PCT/US2017/057309, filed on Oct. 19, 2017(published as WO 2018/075726), entitled Building Automation System, thedisclosure of which is fully incorporated herein by reference. Thisapplication discloses techniques for implementing intelligent electricalreceptacles which can be extended using intelligent circuit breakers asdiscussed herein for enhanced safety and security, power metering, powercontrol, and home diagnostics.

In some embodiments, the master processor is configured to control andmanage the IoT communication for all intelligent circuit breakers andcomponents within the distribution panel, and communicate to theindividual intelligent circuit breakers within the distribution panelusing wire communications (e.g., Controller Area Network (CAN) bus) orbus) or using wireless communication to individual intelligent breakerswithin the distribution panel using a local Bluetooth Low-Energy (BLE)mesh network, with the master processor implementing or otherwiseutilizing any suitable broadband communications technology tocommunicate to remote IoT devices, systems, etc.

FIG. 13 is an exploded view of a circuit breaker housing structure 1300which can be utilized to house switches, circuitry, sensors, and othercomponents of an intelligent circuit breaker, according to an embodimentof the disclosure. The housing structure 1300 comprises a first housingmember 1301, a heat sink element 1302, and a second housing member 1303.The heat sink element 1302 is disposed within the housing structure 1300formed by the coupling of the first and second housing members 1301 and1303. The first and second housing members 1301 and 1303 comprise moldedplastic enclosures for the heat sink element 1302 and other componentsof the circuit breaker. The heat sink element 1302 is formed of ametallic material such as aluminum, or other suitable materials oralloys that would have sufficient thermal conductivity for the givenapplication.

The first housing member 1301 comprises a plurality of open slots1301-1, and the heat sink element 1302 comprises a plurality of coolingfins 1302-1. When the housing structure 1300 is assembled, the coolingfins 1302-1 of the heat sink element 1302 are aligned with correspondingslots 1301-1 of the first housing member 1301 to enable an air-cooledheat sink mechanism. The various integrated circuit chip components(e.g., processor, solid-state bidirectional switch, etc.) are thermallycoupled to the heat sink element 1302 to serve as a cooling plate forthe integrated circuit chips. The integrated heat sink cooling allowsfor enhanced thermal exchange and a relaxation in the total ONresistance of the solid-state bidirectional switch during heavy circuitbreaker load conditions. A line neutral wire (not shown) is added in thetraditional industry-standard approach used for AFCI and GFCI productsand for intelligent circuit breakers. One skilled in the art willrecognize that the various circuits, algorithms, heat exchangers, andother aspects of the disclosed configuration of intelligent circuitbreakers can be adjusted to various form factors required in otherlocations or countries.

FIG. 14 is a flow diagram of a process which is implemented by anintelligent circuit breaker to monitor energy usage on a branch circuitand protect against fault conditions on the branch circuit, according toan embodiment of the disclosure. In some embodiments, FIG. 14illustrates an automated process that is implemented by the intelligentpower distribution and monitoring system 1200 of FIG. 12 when theutility supply power is in a normal state (e.g., no power outage) (block1400). The intelligent circuit breakers will utilize intelligent energymetering methods as discussed herein to monitor energy usage profiles ofthe circuit breakers and intelligent receptacles or electrical devices(block 1401). Based on the monitored energy usage, if an intelligentcircuit breaker determines that a given load has an imminent faultcondition (affirmative determination in block 1402), the intelligentcircuit breaker will communicate with the intelligent receptacle ordevice to automatically disable power delivery to the given load (block1403). In some embodiments, an “imminent fault” comprises a user/machineprogrammable threshold (e.g., determined using artificial intelligencetechniques based on historical information). In this instance, theintelligent circuit breaker would compare the monitored energy usage toa programmed threshold setting (or “Imminent Fault Threshold”) that isheld in the device being monitored. The intelligent circuit breakers (ormaster processor) will send an alert signal or notification of theautomated action to one or more user computing devices to notify usersof the action taken (block 1404).

For example, assume an intelligent circuit breaker or sensor which isintelligently connected to downstream electrical devices, detects anunsafe condition at a specific receptacle or load. By way of specificexample, a 20 Amp circuit breaker typically feeds numerous downstreamreceptacles. Each of these receptacles may be 15 Amp rated devices withthe assumption that a 20 Amp load is shared across multiple receptacles.Sensors in the intelligent circuit breaker may alert a particular smartreceptacle, smart load, or property owner to an unsafe condition, suchas overloaded and daisy-chained power strips, or too many strings ofholiday lights on a single receptacle. In this instance, the intelligentcircuit breaker could issue a wireless alert/notification, or direct thereceptacle to disconnect, or simply trip the breaker itself until thesituation is rectified and reset.

FIG. 15 is a flow diagram of a process which is implemented by anintelligent circuit breaker to monitor energy usage on a branch circuitand protect against fault conditions on the branch circuit, according toan embodiment of the disclosure. FIG. 15 illustrates an automatedprocess that is implemented by the intelligent power distribution andmonitoring system 1200 of FIG. 12 when the utility supply power is in anormal state (e.g., no power outage) (block 1500). The intelligentcircuit breakers will utilize intelligent energy metering methods asdiscussed herein to monitor energy usage profiles of the circuitbreakers and intelligent receptacles or electrical devices (block 1501).When a breaker trip or fault event occurs on given branch circuit whichcauses loss of power on the branch circuit, the intelligent circuitbreaker that protects the given branch circuit will communicate with theintelligent devices (e.g., intelligent receptacles and load devices) onthe given branch circuit and command such intelligent devices to disablepower to the load devices (block 1502).

The intelligent circuit breaker will wait for a predetermined amount oftime following the fault event (block 1503) and then automaticallyre-energize the branch circuit (block 1504). After power up of thebranch circuit, the intelligent circuit breaker will proceed todetermine or otherwise identify which receptacle or load was the sourceof the fault event (block 1505). The intelligent circuit breaker willcommunicate with the other non-offending receptacles or loads tore-apply power (block 1506).

With this control process, an intelligent circuit breaker, when pairedwith an overloaded intelligent receptacle with an ability to wirelesslycommunicate before re-supplying power to its load, may trip a branchcircuit given a dangerous fault condition, and re-apply powerautomatically by wirelessly directing the offending smart receptacle toremain in a load-disconnected state after power-on. This enables theintelligent circuit breaker to re-energize to continue servicing powerto all the other loads on the branch, while still isolating the fault.As a further example, when an intelligent circuit breaker is paired withintelligent receptacles with more than one individual branch feed orphase and a mechanism to switch between them, the intelligent circuitbreaker can direct an intelligent receptacle to switch branch circuitsin an effort to balance the load and more economically make use of phasebalancing.

In other embodiments, an intelligent circuit breaker can be configuredto identify a type of load that is connected to the circuit breaker andto control the identified load using predefined control rules that arebased on the identified load type, using control circuitry and controlprocesses as disclosed in U.S. patent application Ser. No. 16/340,474,filed on Apr. 9, 2019, entitled “Load Identifying AC Power Supply WithControl and Methods,” the disclosure of which is fully incorporatedherein by reference. For example, FIG. 16 is a schematic block diagramof an intelligent circuit breaker 1600 which is configured to identify atype of load connected to the circuit breaker and to control the load onthe basis of the identified load type, according to an embodiment of thedisclosure. In particular, FIG. 16 schematically illustrates anintelligent circuit breaker 1600 connected between an AC mains 110 and aload 120. The intelligent circuit breaker 1600 comprises a processor1602, a first switch 1604, a second switch 1606, switch controlcircuitry 1608, AC-to-DC converter circuitry 1610, a first voltagesensor 1620, a second voltage sensor 1622, a first current sensor 1630,a second current sensor 1632, a third current sensor 1634, and a fourthcurrent sensor 1636.

The first switch 1604 is serially connected in a hot line path between aline input terminal and a load output terminal of the circuit breaker1600, wherein the line hot 111 of the AC mains 110 is connected the lineinput terminal and the load hot 121 of the load 120 is connected to theload output terminal. The second switch 1606 is serially connected in aneutral line path between the line neutral 112 and the load neutral 122.The line hot 111 of the AC mains 110 is connected to the load hot 121when the first switch 1604 is in a switched-on state and the lineneutral 112 is connected to the load neutral 122 when the second switch1606 is in a switched-on state. As in other embodiments of intelligentdiscussed above, the line neutral 112 (which, for example, is bonded tothe earth ground 114 in the breaker distribution panel) serves as alow-side voltage reference (e.g., ground) for the electronic circuitryof the intelligent circuit breaker 1600.

In some embodiments, the first and second switches 1604 and 1606comprise solid-state bidirectional switches that may be configured usingone of the exemplary switching circuits as discussed above inconjunction with FIGS. 6A-6H. The switch control circuitry 1608 isconfigured to control operation of the first and second switches 1604and 1606 using switch control circuitry and techniques as discussedherein. The load identifying AC power supply includes an AC-to-DCconverter 1610 that supplies power to the current sensors 1630, 1632,1634, and 1636 and to the voltage sensors 1620 and 1622, which acquirethe AC mains data and the load data. The AC-to-DC converter circuitry1610 is configured to provide DC supply power to various circuitry andelements of the intelligent circuit breaker 1600 including the processor1602, the voltage sensors 1620 and 1622, the current sensors 1630, 1632,1634, and 1636, and the switch control circuitry 1608. The AC-to-DCconverter circuitry 1610 can be implemented using the exemplaryframeworks as discussed above in conjunction with FIGS. 4A, 4B, and 5.

The first and second voltage sensors 1620 and 1622 are configured tomonitor the voltage at different points along the hot line path throughthe circuit breaker 1600. For example, as shown in FIG. 16, the firstvoltage sensor 1620 is coupled to the hot line path upstream of thefirst switch 1604 to monitor the AC supply voltage of the AC mains 110,and the second voltage sensor 1622 is coupled to the hot line pathdownstream of the first switch 1604 to monitor the load voltage on thebranch circuit which is connected to, and protected by, the intelligentcircuit breaker 1600. The voltage sensors 1620 and 1622 are each coupledto the processor 1602 by one or more data acquisition and control lines1620-1 and 1622-1, respectively. The voltage sensors 1620 and 1622 canbe implemented using any suitable type of voltage sensing circuitryincluding, but not limited to, zero crossing detector circuits,resistive voltage dividers, etc.

The current sensors 1630, 1632, 1634, and 1636 are configured to monitorthe current at different points along the hot line path and neutral linepath through the circuit breaker 1600. For example, as shown in FIG. 16,the first current sensor 1630 is coupled to the hot line path upstreamof the first switch 1604 to monitor the line side supply current, andthe second current sensor 1632 is coupled to the hot line pathdownstream of the first switch 1604 to monitor the load side supplycurrent. The third current sensor 1634 is coupled to the neutral linepath upstream of the second switch 1606 to monitor the line side returncurrent, and the fourth current sensor 1636 is coupled to the neutralline path downstream of the second switch 1606 to monitor the load sidereturn current. The current sensors 1630, 1632, 1634, and 1636 are eachcoupled to the processor 1602 by one or more data acquisition andcontrol lines 1630-1, 1632-1, 1634-1, and 1636-1, respectively. Thecurrent sensors 1630, 1632, 1634, and 1636 can be implemented using anysuitable type of current sensing circuit including, but not limited to,a current-sensing resistor, a current amplifier, a Hall Effect currentsensor, etc.

The processor 1602 operates in conjunction with the voltage sensors 1620and 1622 and current sensors 1630, 1632, 1634, and 1636 to sample theanalog supply voltage and current waveforms of the AC mains 110 and thevoltage and current waveforms across and through the load 120. Theprocessor 1602 is configured to sample the sensed current and voltagewaveforms at a sampling frequency that is significantly greater than thecycle time of a single period of the power supply voltage of the ACmains 110. The sampling frequency of the voltage and current waveformsare selected as required to distinguish load types. In some embodiments,the sampling frequency is in the kilohertz range. In other embodiments,the sampling frequency is in the megahertz range. In some embodiments, aprogrammed variation of the power (or power modulation) is applied tothe load 120 so as to optimize differentiation in the acquired waveformsbetween anticipated load types.

In some embodiments, the processor 1602 comprises circuitry to capture,process and record the current and voltage samples, wherein thecircuitry comprises comparators, analog-to-digital converters, etc., aswell as data storage elements such as random access memory (RAM), readonly memory (ROM) and other types of solid-state memory andnon-solid-state memory devices as are known in the art. In someembodiments, the processor 1602 comprises control logic and associatedcomputing resources to analyze the recorded current and voltage samples(e.g., neural network analysis and classification of the load data) toidentify a load type of the load 120.

For example, analysis of the sampled current and voltage waveformsincludes matching patterns in the high frequency components of thevoltage and current waveforms from the load 120. In other embodiments,the analysis of the waveforms includes determining a delay in timing ofthe load drawing power after power is first applied to the load. Inother embodiments, analysis comprises classifying the acquiredwaveforms, including high frequency components thereof, into groups thatare indicative of different load types. Non-limiting examples of groupsinclude waveforms indicative of a primarily resistive load, a capacitiveload, an inductive load, loads that include power factor correction andloads that include power control such that there is a delay in the powerto the load at initial application of power form the source.

In other embodiments, the processor 1602 can access and utilized aremote server for analyzing the recorded current and voltage waveformsamples. In this instance, the processor 1602 would transmit therecorded samples (via wired or wireless communication links through anIP (internet protocol) network) to a remote server for processing, andthen receive the process results from the remote server. In someembodiments, the processor 1602 is configured to execute a process flowas illustrated in FIG. 17.

In particular, FIG. 17 is a flow diagram of a method of a loadidentifying and control process which is implemented by an intelligentcircuit breaker, according to an embodiment of the disclosure. Anintelligent circuit breaker having a load type identifying and loadcontrol capability is installed at a target location between the ACmains and a load (block 1700). For illustrative purposes, FIG. 17 willbe described in the context of the intelligent circuit breaker 1600 ofFIG. 16. In some embodiments, the intelligent circuit breaker 1600 isinstalled in a circuit breaker distribution panel. In some embodiments,the intelligent circuit breaker 1600 comprises a device that isinstalled in a separate junction box between the AC mains and the load.In other embodiments, the intelligent circuit breaker 1600 is acomponent of an electrical receptacle. In some embodiments, theintelligent circuit breaker 1600 is a component of an electronic supplystrip or smart extension cord.

Once installed and supply power is applied, the intelligent circuitbreaker 1600 will proceed to monitor the connection of a load (block1701). In response to detecting a load (affirmative determination inblock 1701), the intelligent circuit breaker 1600 will activate theswitches 1604 and 1606 to connect the power supply voltage of the ACmains to the load (block 1702). The intelligent circuit breaker 1600then proceeds to acquire and store various types of data for subsequentanalysis (block 1703). The acquired data is stored in a data storagedevice 1710.

For example, data acquisition comprises recording timing informationwith regard to the time that the load is connected to the AC mains powersupply, the time that power is applied to the load, and the time thatpower is used by the load. In addition, data acquisition comprisesacquiring waveform data. Any data acquired once a load is detected thatis specific to a load is termed “load data.” Load data includes the turnon timing of the load as well as waveform data. Waveform data includesacquiring values of the AC main voltage, the load voltage the loadcurrent and the power consumed by the load as a function of time.

The data is acquired at a frequency which is optimized for detection ofthe type of load. In some embodiments, data is acquired at a frequencythat is a multiple higher than the frequency of the AC mains source. Forexample, in one embodiment, data for a 50 to 60 cycle AC source data isacquired at a kilohertz rate. In other embodiments where high frequencycomponents of the voltage and current waveforms are needed to properlyidentify a given type of load, the data is acquired at a megahertz rate.

In some embodiments, the acquired data is stored in a RAM of theprocessor 1602 for real-time or near real-time processing. In otherembodiments, the acquired data is stored in persistent memory or storagefor subsequent access and analysis, e.g., pattern matching, to identifythe identical or similar loads based upon matching of the waveformpatterns obtained at the first connection of the load (block 1701) withconnection of the same or different loads at later times. In someembodiments, the data storage 1710 is accessible by a plurality ofintelligent circuit breaker devices with load identifying and loadcontrol capabilities. Such storage is accessible by devices that arewired or wirelessly connected to the intelligent circuit breaker 1600 orby transfer of the stored load data from an intelligent circuit breaker1600 to another device such as an intelligent circuit breaker device.

Subsequent to the initial data acquisition (block 1703), the intelligentcircuit breaker 1600 can modulate the power that is supplied to the load(block 1704). In particular, in some embodiments, power modulationcomprises controlling one or more of the switches 1604 and 1606 to varythe power that is delivered to the load. Additional load data isacquired and stored both during and after the power modulation (block1705). The intelligent circuit breaker 1600 proceeds to perform a loadidentification process to identify the load type of the connected loadbased on the acquired load data which is captured, before, during andafter the power modulation (block 1706).

In some embodiments, the load identification process is performed bycomparing the waveforms of the load data with previous acquiredwaveforms in load data of known load devices. In other embodiments, theload identification process is based on both the timing around the turnon of the power to the load, as already discussed, and matching of thewave form data. In other embodiments, a neural network analysis is usedto classify the load data into a category of load types by comparisonwith a library of prior load data. In other embodiments, the loadidentification process can implement any suitable classification processusing a trained model to classify the connected load into a particularcategory of load based upon the phase relationship between the loadvoltage and current wave forms and the AC mains voltage wave form bothbefore, during and after modulation of the power to the connected loadusing the switches 1604 and/or 1606.

For example, a load type of a given load can be classified as one of:

(1) Pure Resistive Load: Voltage and current zero crossing and peaksynchronously both before during and after modulation of the supplyvoltage. Power is reduced when voltage is reduced, power returns topre-modulation level when modulation of supply voltage is stopped andsupply voltage returns to full voltage;

(2) Constant power Resistive load with power correction. Voltage andcurrent peak synchronously before modulation, power is constant before,during and after modulation;

(3) Pure Reactive (capacitive or inductive) load. Voltage and currentare out of phase before, during and after modulation, power is reducedduring modulation of the supply voltage, Power returns to pre-modulationlevel when modulation of supply voltage ends and returns to fullvoltage.

(4) Constant Power Reactive load. Voltage and current are out of phasebefore, during and after modulation, power is constant before, duringand after modulation of the supply voltage.

In some embodiments, modulation of the supply voltage results in areduction of the RMS supply voltage by an amount between 1 and 20%. Insome embodiments, the load identification process (block 1706) furthercomprises determining a confidence level for the identification. In oneembodiment the confidence level is determined by the goodness of fit ofa match of the load data obtained during the data acquisition steps 1703and 1705 with data obtained previously on known loads and stored in datastorage 1701. Once the identification process (block 1706) is complete,a determination is made as to whether the load-type of the connectedload has been properly identified with a given level of confidence andwhether there are control rules associated with the identified type ofload (block 1707). In some embodiments, such determination (block 1707)is done by comparing a confidence level in the identification with apre-selected confidence level defined as positive identification.

If the load is positively identified and there are pre-selected controlrules associated with the identified load (affirmative determination inblock 1707), then the intelligent circuit breaker 1600 can control powerto the connected load according to one or more of the associated controlrules (block 1708). For example, power to the connected load iscontrolled by controlling the switches 1604 and/or 1606 in series withthe load. Non-limiting examples of pre-selected control rules include:

(1) during daylight hours, a pure resistive load such as a light bulb isdimmed to reduce power usage, especially during peak demand;

(2) in constant power load, when load demands drop, the input power willdrop accordingly to minimize the power consumption of no load/minimumload requirements;

(3) in remote location (no human presence), a pure resistive load and aconstant power resistive load will be disconnected and reconnectedautomatically by the demand of the load; and

(4) devices that produce an arc during normal operation (e.g. anelectric motor having brush connections to the rotor) are ignored by anarc-fault circuit interrupter to prevent nuisance disconnects.

In other embodiments, there are a pre-selected set of rules based uponwhether the load type is one of a pure resistive load, a constant powerresistive load, a pure reactive load, and a constant power reactiveload. In one non-limiting example of pre-selected rules, the loadsidentified as having an included power factor correction, that isconstant power loads, are not turned off by the controller, and whilepower to pure resistive loads is turned off during pre-selected periodsof time, and power to pure reactive loads is reduced during pre-selectedperiods of time. On the other hand, if either the load type is notidentified or there are no predefined control rules associated with theidentified load type (negative determination in block 1707), theintelligent circuit breaker will simply maintain the connection of thepower supply and load (block 1709), and disconnect in response to faultconditions as discussed herein.

In other embodiments, an intelligent circuit breaker can be configuredto include fault detection sensors and circuitry to support arc-faultcircuit interrupt (AFCI) and/or ground-fault circuit interrupt (GFCI)functions using control circuitry and methods as disclosed in U.S.patent application Ser. No. 16/093,044, filed on Oct. 11, 2018, entitled“Solid-State Line Disturbance Circuit Interrupter,” the disclosure ofwhich is fully incorporated herein by reference. An intelligent AFCIcircuit breaker according to an embodiment of the disclosure isconfigured to provide protection against parallel arcing (line toneutral), series arcing (a loose, broken, or otherwise high resistancesegment in a given line, and ground arcing (from line, or neutral, toground). An intelligent GFCI circuit breaker according to an embodimentof the disclosure is configured to provide protection againstground-faults which occur when electrical current in given device orappliance leaks from the normal path from line to neutral an appliance.A GFCI circuit breaker monitors the difference in current between thehot and neutral lines, and when the current input to a given load on thehot line is greater that the return current from the load on the neutralline by a predefined amount (e.g., 5 mA), the GFCI breaker will trip tostop of flow of current. FIG. 18A is a schematic block diagram of anintelligent circuit breaker 1800 which is configured to monitor forground-fault and arc-fault conditions and provide circuit interruptionin response to detected fault conditions, according to an embodiment ofthe disclosure. The intelligent circuit breaker 1800 comprises a lowvoltage DC power supply 1804, voltage and current sensing circuitry1820, a control processor 1830, and electronic switch and switch controlcircuitry 1840. The low voltage DC power supply 1810 efficientlyprovides DC power for the voltage and current sensing circuitry 1820,and the control processor 1830. Sense inputs 1820-1 and 1820-2 to thecontrol processor 1830 are provided from the voltage and current sensingcircuitry 1820. The voltage and current sensing circuitry 1820 comprisessensors that sense the waveforms of the voltage and current applied tothe load circuit, and, develop proportional analog waveforms. Thecontrol processor 1830 processes the proportional analog waveforms andupon detection of either a ground-fault or an arc-fault generates afault output on control line 1840-1, which is coupled to switch controlcircuitry 1840. Upon detection of a fault, a fault output signal appliedon control line 1840-1 is latched and fed to a CONTROL input of theswitch control circuitry and causes the electronic switch to disconnectthe load 120 from the AC mains 110 until a reset 1850 is applied to thefault detection control processor 1830.

In other embodiments, an output voltage of the electronic switch 1840can be varied through the switch control circuitry. For example, upondetection of an arc-fault, the output voltage can be reduced to a valuethat is less than a threshold for arcing yet greater than zero. Such anembodiment allows the load circuit to continue operation at a reducedvoltage while reducing the chance for a damaging arc. The operation atreduced voltage also allows for continued characterization of the loadand mains supply circuit to determine the location of an arc-fault forsubsequent replacement or repair.

FIG. 18B is a schematic circuit diagram of the intelligent circuitbreaker 1800 of FIG. 18A, according to an embodiment of the disclosure.In the exemplary embodiment of FIG. 18B, the voltage and current sensingcircuitry (1820, FIG. 18A) comprises a first current sensor 1821, asecond current sensor 1822, a full-wave rectifier 1823, and senseresistors 1824 and 1825. The electronic switch and control circuitry(1840, FIG. 18A) comprises solid-state switch circuitry 1842 (e.g.,solid state bidirectional switch) to connect the AC mains 110 to theload 120, and switch control circuit 1844 that controls the solid-stateswitch circuitry 1842 via an optical signal interface 1844-1. The lowvoltage AC-to-DC power supply 1810 provides DC supply power for thecurrent sensors 1821 and 1822, the fault detection processor 1830, andthe switch control circuitry 1844. The fault detection processor 1830comprises current sense inputs for each of the current sensors 1821 and1822 and voltage sense inputs that sense voltage across the senseresistors 1824 and 1825.

In some embodiments, as shown in FIG. 18B, the first and second currentsensors 1821 and 1822 comprise solid-state Hall Effect sensors whichgenerate an output voltage proportional to the current flowing in theline hot 111 and line neutral 112 paths. The voltages generated by theHall Effect sensor outputs are fed to the current sense inputs of thefault detection processor 1830. Further, in some embodiments, thevoltage sensor comprises a full-wave rectifier bridge 1823 which isconfigured to convert both half cycles of the AC supply voltage waveformof the AC mains 110 into a pulsating DC voltage. The full-wave rectifiedwaveform is attenuated using a resistive divider network comprisingresistors 1824 and 1825 and applied to the voltage sense inputs of thefault detection processor 1830. In some embodiments, the full-waverectifier bridge 1823 can be eliminated and the full-wave rectifiedwaveform obtained directly from the output of the AC-DC convertercircuit 1810.

Upon detection of a fault by the fault detection processor 1830, a faultoutput of the fault detection processor 1830 is latched and fed to acontrol input of the switch control circuitry 1844, which then generatesan optical control signal 1844-1 to the solid-state bidirectional switchcircuitry 1842 to disconnect the load 120 from the AC mains 110 until areset switch 1850 is activated to reset the fault detection processor1830. As noted above, in other embodiments, the output voltage of thesolid-state switch circuitry 1842 is varied through the switch controlcircuitry 1844 such that upon detection of an arc-fault, the outputvoltage is reduced to a value that is less than a threshold for arcingyet greater than zero. This allows the load 120 to continue operation ata reduced voltage while reducing the chance for a damaging arc. Theoperation at reduced voltage also allows for continued characterizationof the load and mains supply circuit to determine the location of anarc-fault for subsequent replacement or repair.

FIG. 19 is a schematic block diagram of a fault detection processor 1900which can be implemented in the intelligent circuit breaker of FIG. 18B,according to an embodiment of the disclosure. The fault detectionprocessor 1900 comprises input resistors 1902 and 1904, amplifiers 1910,1912, and 1914, A/D converters 1920, 1922, and 1924, a voltage anomalydetection module 1930, a current anomaly detection module 1932, athreshold detection module 1934, an AND gate 1940, an OR gate 1950, anda latch circuit 1960. The voltage sense signals are applied to theinverting and non-inverting input terminals of the amplifier 1910. Theamplifier 1910 is configured as a differential amplifier which generatesa difference signal ΔV that is input to the A/D converter 1920. Thecurrent sense inputs are applied to the non-inverting input of theamplifier 1912 through the resistors 1902 and 1904. The sense inputs aresummed by the input circuit (1902, 1904) and the operational amplifier1912 outputs a signal that is proportional to the sum of the currents ΣIin the line and neutral legs of the AC mains 110. The ΣI signal is alsoapplied to the input of the A/D converter 1922. The digitized ΔV signalis processed by the voltage anomaly detection module 1930 (e.g.,subprogram) that is executed by the fault detection processor 1900 todetect anomalies in the voltage waveform over several cycles thatindicate the presence of an arc-fault. One non-limiting example of sucha voltage anomaly is the presence of excess high frequency energyimpressed upon the normally low frequency AC mains voltage waveform.

The digitized ΣI signal is processed by the current anomaly detectionmodule 1932 (subprogram) that is executed by the fault detectionprocessor 1900 to detect anomalies in the current waveforms over severalcycles that indicate the presence of an arc-fault. One non-limitingexample of such a current anomaly is the occurrence of “shoulders” (flatspots) in the current waveform that occur near zero-crossings of thecurrent waveform. The outputs of the detection modules 1930 and 1932 areinput to the AND gate 1940, wherein a combined appearance of a voltagewaveform anomaly and a current waveform anomaly is one indicator of anarc-fault.

The current sense signals are also applied to the inputs of theamplifier 1914 which forms a difference signal ΔI proportional to thedifference between the currents in the line and neutral legs. The ΔIsignal is digitized by the A/D converter 1924 and processed by thethreshold detection module 1934 which generates a threshold detectionsignal which indicates a ground-fault. The arc-fault signal at theoutput of the AND gate 1940 and the ground-fault signal at the output ofthe threshold detection module 1934 are logically OR'ed via the OR gate1950, and the output of the OR gate 1950 is input to the latch circuit1960. The latch circuit 1960 outputs a fault detection signal and storesthe fault condition until cleared by an external reset signal.

FIG. 20 schematically illustrates a current zero-crossing detectorcircuit according to an embodiment of the disclosure. In particular,FIG. 20 schematically illustrates a current zero-crossing detectorcircuit 2000 comprising a polarity change detection stage 2010, an edgedetection stage 2020, an output stage 2030, and a sense resistor 2040.In some embodiments, the sense resistor 2040 is connected in series inan electrical path between the line hot 111 and the load hot 121. Thepolarity change detection stage 2010 comprises a first comparator 2011and a second comparator 2012. The edge detection stage 2020 comprises afirst edge detection circuit 2020-1 connected to an output of the firstcomparator 2011, and a second edge detection circuit 2020-2 connected toan output of the second comparator 2012. The first and second edgedetection circuits 2020-1 and 2020-2 comprise respective inverters 2021and 2022, respective resistors 2023 and 2034, respective capacitors 2025and 2026, and respective exclusive-OR (XOR) gates 2027 and 2028. Theoutput stage 2030 comprises an AND gate 2032 having inputs connected tothe outputs of the XOR gates 2027 and 2028 of the edge detection stage2020.

The sense resistor 2040 generates an AC voltage (referred to as sensevoltage, V_(Sense)) across a first node N1 (line side node) and a secondnode N2 (load side node) based on an AC load current that flows throughthe sense resistor 2040 in the electrical path between the line hot 111and the load hot 121. As noted above, in some embodiments, the senseresistor 2040 comprises a high-power resistor that has a relatively lowresistance value which can generate a sufficient sense voltage acrossthe sense resistor 2040 for purposes of measurement, while not consuminga large amount of energy. For example, in some embodiments, the senseresistor 2040 comprises a resistance value of about 1 milli-Ohm. In someembodiments, the sense resistor 2040 shown in FIG. 20 is the same senseresistor 922 shown in FIG. 9A, wherein multiple detection circuits of anintelligent circuit breaker are tapped off the same sense resistor toprovide various functionalities.

The polarity change detection stage 2010 is configured to detect apolarity change of the sense voltage V_(Sense) that is generated acrossthe sense resistor 2040 as a result of AC current flow through the senseresistor 2040. The first and second comparators 2011 and 2012 are eachconfigured as a voltage comparator which compares a reference voltageapplied to an inverting input (−) of the comparator with an inputvoltage applied to a non-inverting input (+) of the comparator, andgenerates a logic “1” output when the input voltage is greater than thereference voltage, and generates a logic “0” output when the inputvoltage is less than the reference voltage. More specifically, in theexemplary embodiment of FIG. 20, the first comparator 2011 comprises anon-inverting input (+) connected to a load side (node N2) of the senseresistor 2040 and an inverting input (−) connected to a line side (nodeN1) of the sense resistor 2040. The second comparator 2012 comprises anon-inverting input (+) connected to the line side (node N1) of thesense resistor 2040 and an inverting input (−) connected to the loadside (node N2) of the sense resistor 2040.

During positive half-cycles of the voltage waveform of the AC mains 110,positive current flows through the sense resistor 2040 from node N1 tonode N2, which results in a positive sense voltage (+V_(Sense)) dropacross the sense resistor 2040 (i.e. VN1−VN2>0). With a positive sensevoltage (+V_(Sense)), an output compare signal C1 of the firstcomparator 2011 will be logic “0”, and an output compare signal C2 ofthe second comparator 2012 will be logic “1.” On the other hand, duringnegative half-cycles of the voltage waveform of the AC mains 110,negative current flows through the sense resistor 2040 from node N2 tonode N1, which results in a negative sense voltage (−V_(Sense)) dropacross the sense resistor 2040 (i.e., VN1−VN2<0). With a negative sensevoltage (−V_(Sense)), the output compare signal C1 of the firstcomparator 2011 will be logic “1”, and the output compare signal C2 ofthe second comparator 2012 will be logic “0”.

When the sense voltage V_(Sense) transitions from positive (+V_(Sense))to negative (−V_(Sense)), the output compare signal C1 of the firstcomparator 2011 transitions from logic 0 to logic 1, and the outputcompare signal C2 of the second comparator 2012 transitions from logic 1to logic 0. On the other hand, when the sense voltage V_(Sense)transitions from negative (−V_(Sense)) to positive (+V_(Sense)), theoutput compare signal C1 of the first comparator 2011 transitions fromlogic 1 to logic 0, and the output compare signal C2 of the secondcomparator 2012 transitions from logic 0 to logic 1.

The transitions (or edges) of the compare signals C1 and C2 are detectedby the respective edge detection circuits 2020-1 and 2020-2 of the edgedetection stage 2020. More specifically, in the first edge detectioncircuit 2020-1, the XOR gate 2027 has a first input terminal whichreceives the compare signal C1, and a second input terminal whichreceives a delayed complementary compare signal C1 ′. The delayedcomplementary compare signal C1 ′ is generated by the inverter 2021 anda delay circuit implemented by the resistor 2023 and the capacitor 2025,wherein the inverter 2021 is configured to generate and output aninverted (complementary) compare signal C1 , and wherein the resistor2023 and the capacitor 2025 are configured to apply an RC delay to thecomplementary compare signal C1 and thereby generate the delayedcomplementary compare signal C1 ′. In an exemplary embodiment, theresistor 2023 has a resistance of 1 kilo-ohm, and the capacitor 2025 hasa capacitance of 3.3 nano-farads. The XOR gate 2027 generates a shortlogic 0 edge pulse signal E1 during a period of time when the inputsignals C1 and C1 ′ have the same logic level (e.g., both logic 0 orboth or logic 1).

Similarly, in the second edge detection circuit 2020-2, the XOR gate2028 has a first input terminal which receives the compare signal C2,and a second input terminal which receives a delayed complementarycompare signal C2 ′. The delayed complementary compare signal C2 ′ isgenerated by the inverter 2022 and a delay circuit implemented by theresistor 2024 and the capacitor 2026, wherein the inverter 2022 isconfigured to generate and output an inverted (complementary) comparesignal C2 , and wherein the resistor 2024 and the capacitor 2026 areconfigured to apply an RC delay to the complementary compare signal C2and thereby generate the delayed complementary compare signal C2 ′. Inan exemplary embodiment, the resistor 2024 has a resistance of 1kilo-ohm, and the capacitor 2026 has a capacitance of 3.3 nano-farads.The XOR gate 2028 generates a short logic 0 edge pulse signal E2 duringa period of time when the input signals C2 and C2 ′ have the same logiclevel (e.g., both are logic 0 or both are logic 1).

In operation, the XOR gates 2027 and 2028 generate the respective edgepulse signals E1 and E2 just prior to the current zero-crossing and justafter the zero-current crossing. The AND gate 2032 has first and secondinput terminals connected to the respective outputs of the XOR gates2027 and 2028. The AND gate 2032 generates and outputs a currentzero-crossing detection signal Zi based on a logical ANDing of theoutput signals E1 and E2. The current zero-crossing detection signal Ziis applied to switch control circuitry which controls one or moreswitches (e.g., solid-state bi-directional switch and/or a solenoid ofan electromechanical switch) of the intelligent circuit breaker. In theexemplary circuit configuration of FIG. 20, the AND gate 2032 outputstwo zero-going pulses, one before and one after current zero-crossing.The two pulses are closer together with increasing sense current. Atlarge currents (e.g., 100 amps), the two pulses are essentially onepulse. Given that the outputs of the edge detection circuits 2020-1 and2020-2 are “ground-true,” the AND gate 2032 in this configurationfunctions as “ground-true” OR gate because anytime a logic “0” is on oneof the inputs of the AND gate 2032, the output of the AND gate 2032 willbe logic “0.”

FIGS. 21A and 21B depict various waveforms that illustrate operatingmodes of the current zero-crossing detection circuit of FIG. 20,according to an embodiment of the disclosure. For example, FIG. 21Adepicts waveforms that illustrate a mode of operation of the edgedetection stage 2020 of FIG. 20, in particular, an operating mode of thefirst edge detection circuit 2020-1. In particular, FIG. 21A illustratesa timing diagram for plurality of signal waveforms 2100, 2110, 2120, and2130, wherein waveform 2100 represents an exemplary compare signal C1which is generated by the first comparator 2011, wherein waveform 2110represents an exemplary complementary compare signal C1 which outputfrom the inverter 2021, wherein waveform 2120 represents an exemplarydelayed complementary compare signal C1 ′ which is generated as a resultof the RC delay circuit at the output of the inverter 2021, and whereinwaveform 2130 represents an exemplary edge detection signal E1 that isgenerated by the XOR gate 2027 in response to the waveforms 2100 and2120 applied to the inputs of the XOR gate 2027.

As shown in FIG. 21A, the waveform 2130 of the edge detection signal E1generates a zero-going pulse in response to each logic transition of thewaveform 2100 of the compare signal C1 output from the first comparator2011. The edge detection circuit 2020-2 operates in a similar manner tothe edge detection circuit 2020-1, as depicted in the timing diagram ofFIG. 21A. In particular, the waveforms 2100, 2110, 2120, and 2130 canrepresent, respectively, the compare signal C2 generated by the secondcomparator 2012, the complementary compare signal C2 generated by theinverter 2022, the delayed complementary compare signal C2 ′ generatedby the RC delay circuit (resistor 2024, and capacitor 2026), and theedge detection signal E2 output from the XOR gate 2028 in response tothe waveforms C2 and C2 ′ applied to the inputs of the XOR gate 2028. Itis to be understood that the waveforms 2100, 2110, 2120, and 2130 aregenerically depicted in FIG. 21A and do not take into account, e.g.,slew rates (of rising and falling edges) of the signals, propagationdelays through the logic gates, etc.

FIG. 21B illustrates simulated signal waveforms that illustrate anoperating mode of the current zero-crossing detection circuit 2000 ofFIG. 20, according to an embodiment of the disclosure. In particular,FIG. 21B illustrates a timing diagram for plurality of simulated signalwaveforms 2140, 2150, 2160, 2170, 2180, and 2190. The waveform 2140represents an exemplary current waveform of load current that flowsthrough the sense resistor 2040. The waveform 2150 represents anexemplary compare signal C1 which is generated by the first comparator2011. The waveform 2160 represents an exemplary compare signal C2 whichis generated by the second comparator 2012. The waveform 2170 representsan exemplary edge detection signal E1 generated by the first edgedetection circuit 2020-1. The waveform 2180 represents an exemplary edgedetection signal E2 generated by the second edge detection circuit2020-2. The waveform 2190 represents a current zero-crossing detectionsignal Zi which is generated by the AND gate 2032 in response to thewaveforms (D) and (E). In addition, FIG. 21B depicts a Z-REF dashedline, which represents a time of a current zero crossing of the currentwaveform 2140.

In FIG. 21B, the waveform 2140 of the load current is shown to rise fromnegative to positive, which indicates a transitioning of the AC currentwaveform through the sense resistor 2040 from a negative half-cycle to apositive half-cycle. In this instance, the sense voltage, V_(Sense),transitions from negative (−V_(Sense)) to positive (+V_(Sense)). Inreality, the zero cross of the load current through the sense resistor2040 does not necessarily coincide with the zero cross of the voltage,as there can be a phase difference between the voltage and current dueto, e.g., an inductive load (current phase trails voltage phase) orother instances when the power factor is less than 1 resulting in aphase difference between the load current and voltage waveforms.

As shown in FIG. 21B, the waveform 2150 illustrates the first comparesignal C1 transitioning from logic “1” to logic “0” in response to atransitioning of the sense voltage VSense from negative to positive, andthe waveform 2160 illustrates the second compare signal C2 transitioningfrom logic “0” to logic “1” in response to the transitioning of thesense voltage V_(Sense) from negative to positive. Further, the waveform2170 illustrates that the first edge detection signal E1 output from theXOR gate 2027 comprises a short zero-going edge detection pulse 2171which corresponds to the edge transition of the first compare signal C1of waveform 2150. Similarly, the waveform 2180 illustrates that thesecond edge detection signal E2 output from the XOR gate 2028 comprisesa short zero-going edge detection pulse 2182 which corresponds to theedge transition of the second compare signal C2 of waveform 2160.

It is to be noted that as shown in FIG. 21B, the falling edge of firstcompare signal C1 waveform 2150 precedes the zero current cross Z-REFand that the rising edge of the second compare signal C2 of waveform2160 follows the zero current cross Z-REF. On a negative going cycle ofthe load current 2140 (not specifically shown), the roles reverse. Inparticular, the falling edge of the second compare signal C2 willprecede the zero crossing of the load current, and the rising edge offirst compare signal C1 will follow the zero crossing of the loadcurrent. This is due to asymmetry in the rising edge and falling edgepropagation delay of the comparator circuitry in the polarity changedetection stage 2010, and is a reason for the dual circuitconfiguration.

Moreover, the waveform 2190 of the zero-crossing detection signal Zicomprises a first zero-crossing detection pulse 2191 (zero-going pulse)and a second zero-crossing detection pulse 2192 (zero-going pulse) whichare generated just before and just after the actual zero-crossing of theload current waveform 2140. As noted above, the waveform 2190 of thezero-crossing detection signal Zi is generated by logically ANDing thewaveforms 2170 and 2180 of the edge detection signals E1 and E2, whereinthe first zero-crossing detection pulse 2191 corresponds to the firstedge detection pulse 2171 in the E1 waveform 2170, and wherein thesecond zero-crossing detection pulse 2192 corresponds to the second edgedetection pulse 2182 in the E2 waveform 2180. In this regard, as notedabove, in the exemplary circuit configuration of FIG. 20, the AND gate2032 outputs two zero-going pulses 2191 and 2192, one before and oneafter the current zero-crossing.

Further simulations show that the zero-crossing detection pulses movecloser together with increasing load current through the sense resistor2040. At large currents (e.g., 100 amps), the two zero-crossingdetection pulses are essentially one pulse, and are generated atessentially the same time as the actual current zero-crossing, where theload current through the sense resistor 2040 is substantially oractually zero. In particular, as the load current increases, the slopeof the load current (dv/dt) increases. A benefit of the currentzero-crossing detector circuit 2000 of FIG. 20 is that as the loadcurrent increases, the dual negative going pulses of Zi move closer intime towards one another and towards the point in time of the currentzero crossing. Given that a goal of an intelligent circuit breaker (inwhich the current zero-crossing detector circuit 2000 is integrated) isto open an AC switch as close in time to the zero crossing as possible,it is beneficial to utilize the first of the dual pulses of Zi (as itprecedes the zero current cross) to invoke action and get “head start”to open the AC switch, given that there are unavoidable delays in theswitch control circuitry that invokes such action. In addition, as notedabove, another benefit is that the pulses of Zi are closest to thecurrent zero crossing when it is most important, at high current loads.At the highest loads (e.g. greater than 100 A) the dual pulses of Zimove so close together that they essentially merge into one pulse thatis nearly coincident with current zero crossing.

FIG. 22 schematically illustrates a short-circuit detection circuitaccording to an embodiment of the disclosure. In particular, FIG. 22schematically illustrates a short-circuit detection circuit 2200comprising a first comparator 2202, a second comparator 2204, a NOR gate2210, a plurality of resistors 2212, 2213, 2213, and 2215, and a senseresistor 2040. The sense resistor 2040 is connected in series betweennodes N1 and N2 in the electrical path between the line hot 111 and theload hot 121. In some embodiments, the sense resistor 2040 is the samesense resistor 2040 that is utilized for the current zero-crossingdetector circuit 2000 of FIG. 20.

The first comparator 2202 comprises a non-inverting input (+) connectedto a load side (node N2) of the sense resistor 2040 and an invertinginput (−) connected to a node N3 between the resistors 2212 and 2213.The second comparator 2204 comprises a non-inverting input (+) connectedto the line side (node N1) of the sense resistor 2040 and an invertinginput (−) connected to a node N4 between the resistors 2214 and 2215.The resistors 2212 and 2213 implement a first voltage divider circuit(connected across VDC on Hot and node N1) which is configured togenerate a first reference voltage VREF1 at node N3 which is applied tothe inverting input (−) of the first comparator 2202. The resistors 2214and 2215 implement a second voltage divider network (connected acrossVDC on Hot and node N2) which is configured to generate a secondreference voltage VREF2 at node N4 which is applied to the invertinginput (−) of the second comparator 2204. The first and secondcomparators 2202 and 2204 have output terminals connected to inputterminals of the NOR gate 2210.

In operation, the first comparator 2202 compares the sense voltageV_(Sense) at node N2 with the first reference voltage VREF1 andgenerates and outputs a first compare signal HC1. The second comparator2204 compares the sense voltage V_(Sense) at node N1 with the secondreference voltage VREF2 and generates and outputs a second comparesignal HC2. The NOR gate 2210 logically NOR's the first and secondcompare signals HC1 and HC2 to generate and output a high-currentdetection signal HC which is applied to switch control circuitry whichcontrols one or more switches (e.g., solid-state bi-directional switchand/or a solenoid of an electromechanical switch) of the intelligentcircuit breaker.

More specifically, the first comparator 2202 generates and outputs alogic “1” signal (HC1) when the sense voltage V_(Sense) at node N2exceeds the first reference voltage VREF1, and the second comparator2204 generates and outputs a logic 1 signal (HC2) when the sense voltageV_(Sense) at node N1 exceeds the second reference voltage VREF2. Inother words, in the exemplary embodiment of FIG. 22, the firstcomparator 2202 is configured to detect an extreme over-currentcondition of the load (i.e., short-circuit) during negative half-cyclesof the AC supply voltage waveform, and the second comparator 2204 isconfigured to detect an extreme over-current condition of the load(i.e., short-circuit) during positive half-cycles of the AC supplyvoltage waveform. The NOR gate 2210 will output a logic “0” signal (HC)when either of the half-cycles is detected to have an extremeover-current condition (e.g., when either HC1 or HC2 is logic “1”).

The resistance values of the resistors 2212, 2213, 2214 and 2215 areselected to generate reference voltages VREF1 and VREF2 which allow theshort-circuit detection circuit 2200 to detect over-current conditionsthat exceed a target over-current threshold level. For example, for a 20A breaker, the short-circuit detection circuit 2220 can be configured todetect short-circuit conditions in which the load current is 200 A ormore. The ratio of the resistance values of resistors 2212 and 2213 isselected to achieve a desired value of the first reference voltageVREF1, and the ratio of the resistance values of resistors 2214 and 2215is selected to achieve a desired value of the second reference voltageVREF2. In some embodiments, the resistance value of the resistor 2215 isselected to be substantially equal to a resistance value of theresistors 2212 and 2213 in parallel, which effectively compensates forthe voltage drop across the sense resistor 2040.

FIG. 23 illustrates simulated signal waveforms that illustrate a mode ofoperation of the short-circuit detection circuit 2200 of FIG. 22,according to an embodiment of the disclosure. In particular, FIG. 23illustrates a timing diagram for plurality of signal waveforms 2300,2310, 2320, and 2330. The waveform 2300 represents an exemplary firstcompare signal HC1 which is generated by the first comparator 2202. Thewaveform 2310 represents an exemplary second compare signal HC2 which isgenerated by the second comparator 2204. The waveform 2320 represents anexemplary high-current detection signal HC which is generated by the NORgate 2210. The waveform 2330 represents a simulated AC current waveformof load current that flows through the sense resistor 2040.

In the exemplary embodiment of FIG. 23, it is assumed that theshort-circuit detection circuit 2200 is configured to detectover-current conditions when the load current waveform 2330 reaches orexceed 200 A or more in either half-cycle. As shown in FIG. 23, thewaveform 2300 illustrates that the first compare signal HC1 is set to alogic “1” level during a period of time in each negative half-cycle inwhich the load current waveform 2330 reaches or exceeds 200 A. Thewaveform 2310 illustrates that the second compare signal HC2 is set to alogic “1” during a period of time in each positive half-cycle in whichthe load current waveform 2330 reaches or exceeds 200 A. The waveform2320 illustrates the high-current detection signal HC which is generatedby logically NOR'ing the waveforms 2300 and 2310. In this exemplaryembodiment, the waveform 2320 illustrates that the NOR gate 2210generates a logic “0” pulse for each period of time in which the loadcurrent waveform 2330 reaches and exceeds 200 A in either half-cycle ofthe load current.

It is to be appreciated that the hardware detection circuits of FIGS. 20and 22 allow for fast and efficient detection of current zero-crossingevents, and fast and efficient detection and response to extremeover-current and short-circuit conditions. While such detection can beimplemented using software that is executed by a processor, the use ofthe hardware detection enables fast detection and response times and, ascompared to the delay in the detection and response that may occur as aresult of the indeterministic processing time that a processor mightimpose by analyzing sensor data using software. In addition, the currentzero-crossing detection circuit 2000 of FIG. 20 allows an intelligentcircuit breaker to place a solid-state switch in a switched-off state ata time when the load current is at a near zero. In this instance, thesolid-state switch can be switched-off when the load current is at anear zero to avoid kick-back from inductive loads, wherein high-voltagekick-back spikes can damage the MOSFETS of the solid-state switch or theMOSFETs of a leakage clamp (e.g., isolation circuitry 810, FIG. 8B). Thehardware detection circuits of FIGS. 20 and 22 are powered by a DCsupply (e.g., VDC-on-Hot) that is referenced from the line hot 110. Thisprovides the advantage of avoiding the delay that comes withopto-isolators or other circuits that would be required if thesecircuits were powered from a neutral-referenced DC power supply.

FIG. 24 schematically illustrates an intelligent circuit breakeraccording to another embodiment of the disclosure. In particular, FIG.24 schematically illustrates an intelligent circuit breaker 2400connected between an AC mains 110 and a load 120, wherein theintelligent circuit breaker 2400 comprises a single pole hybridsolid-state and mechanical circuit breaker architecture. The intelligentcircuit breaker 2400 comprises a solid-state switch 2410 and an air-gapelectromagnetic switch 2420 connected in series in an electrical pathbetween the line hot 111 of the AC mains 110 and the load hot 121 of theload 120 (e.g., the air-gap electromagnetic switch 2420 and thesolid-state switch 2410 are connected in series between a line inputterminal and a load output terminal of the intelligent circuit breaker2400). The intelligent circuit breaker 2400 further comprises anAC-to-DC converter circuit 2430, a zero-crossing detection circuitry2440, a sense resistor 2442, a current sensor 2450, other types ofsensors 2460 (e.g., environmental sensors, light sensors, etc.), and aswitch controller 2470.

In some embodiments as shown in FIG. 24, the solid-state switch 2410comprises a power MOSFET switch 2410 (e.g., N-type enhancement MOSFETdevice) having gate terminals (G), drain terminals (D), and sourceterminals (S) as shown, and an intrinsic body diode 2410-1. The air-gapelectromagnetic switch 2420 comprises any suitable type ofelectromagnetic switch mechanism which is configured to physically openand close a set of electrical contacts, wherein an air gap is createdbetween the electrical contacts when the air-gap electromagnetic switch2420 is in a switched-open state. For example, the air-gapelectromagnetic switch 2420 may comprise a latching solenoid or relaycontact element that is responsive to control signals from the switchcontroller 2470 to automatically open or close the electrical contactsof the air-gap electromagnetic switch 2420.

The creation of an air gap in the line path between the line hot 111 andload hot 121 provides complete isolation of the AC mains 110 from theload 120, as it prevents the flow of current from the line hot 111 tothe load hot 121. The air-gap electromagnetic switch 2420 may bedisposed on either the line side (as shown in FIG. 24) of thesolid-state switch 2410 or on the load side of the solid-state switch2410. The intelligent circuit breaker 2400 provides a cost-effectivesolution which allows one solid-state switch to be utilized (as comparedto several solid-state switches in the exemplary embodiments describedabove) in an instance where electrical codes require the implementationof an air-gap in the circuit breaker for complete isolation.

The AC-to-DC converter circuitry 2430 is configured to provide DC supplypower to various circuitry and elements of the intelligent circuitbreaker 2400 including the zero-crossing detection circuitry 2440, theswitch controller 2470, and optionally the current sensor 2450 and othersensors 2460 (depending on the configuration of such sensors 2450 and2460). The AC-to-DC converter circuitry 2430 is configured to remainpowered during faults when the solid-state switch 2410 is in aswitched-off state or when the electromagnetic switch 2420 is in aswitched-open state. In some embodiments, the AC-to-DC convertercircuitry 2430 comprises sufficient storage capacitance to power the DCsubsystems immediately following a utility outage such that relevantpower outage or short-circuit information may be obtained and stored bythe switch controller 2470 as the utility power collapses, and thenwirelessly transmitted to a remote node, device, or system using a radiofrequency transceiver (not shown) which is either coupled to the switchcontroller 2470 or integrated with the switch controller 2470.

In some embodiments, the zero-crossing detection circuitry 2440 isconfigured to monitor the voltage and/or current at a target point alongthe hot line electrical path of the intelligent circuit breaker 2400 anddetect zero current and/or zero voltage crossings of the AC waveform onthe hot line electrical path. For example, as shown in FIG. 24, thezero-crossing detection circuitry 2440 is coupled to the hot lineelectrical path upstream of the switches 2420 and 2410 to detectinstances of zero current and/or zero voltage crossings of the AC powerwaveform on the line side of the intelligent circuit breaker 2400. Thezero-crossing detection circuitry 2440 is coupled to the switchcontroller 2470 by one or more data acquisition and control lines2440-1.

The zero-crossing detection circuitry 2440 can be implemented using anysuitable type of voltage zero-crossing and/or current zero-crossingdetection circuitry that is configured to sense zero crossings ofcurrent and/or voltage of the AC power supply waveform and generate adetection signal which indicates a zero-crossing event and an associatedtransition direction of the zero-crossing event of the current orvoltage waveform (e.g., the AC waveform transitioning from negative topositive (referred to as “positive transition direction”), or the ACwaveform transitioning from positive to negative (referred to as a“negative transition direction”)).

In some embodiments, the zero-crossing detection circuitry 2440 isconfigured to receive as input a sampling of the AC waveform on the hotline path (on the line side of the switches 2420 and 2410), compare theAC waveform sample to a zero reference voltage (e.g., line neutralvoltage) to determine the polarity of the AC waveform on the hot linepath, and detect a zero-crossing event and the associated transitiondirection of the zero-crossing of the AC waveform. In some embodiments,the comparing is performed using a voltage comparator which has anon-inverting input connected to the hot line path, and an invertinginput that receives a reference voltage. The output of the voltagecomparator switches (i) from logic 1 to logic 0 when the input voltagetransitions from positive to negative and (ii) from logic 0 to logic 1when the input voltage transitions from negative to positive. In thisinstance, the output of the zero-crossing detection circuitry 2440 willtransition between a logic “1” and logic “0” output upon each detectedzero crossing of the AC voltage waveform.

In some embodiments, the zero-crossing detection circuitry 2420implements the current zero-crossing detection circuit 2000 of FIG. 20.In this instance, the sense resistor 2442 in FIG. 24 is utilized in amanner similar to the sense resistor 2040 shown in FIG. 20. The currentzero-crossing detection circuitry is utilized instead of, or in additionto, a voltage zero-crossing detection circuitry to determine when the ACcurrent waveform (i.e., AC load current) on the hot line is zero and thetransition direction of the AC current waveform. This is desired ininstances, for example, when there is an inductive load which causes thevoltage and current waveforms on the hot line path to be out of phase.

In some embodiments, the current sensor 2450 is configured to detect amagnitude of current being drawn by the load 120 in the hot line paththrough the intelligent circuit breaker 2400. The current sensor 2450can be implemented using any suitable type of current sensing circuitincluding, but not limited to, a current-sensing resistor, a currentamplifier, a Hall Effect current sensor, etc. The current sensor 2450 iscoupled to the switch controller 2470 by one or more data acquisitionand control lines 2450-1. In some embodiments, the current sensor 2450implements the short-circuit detection circuit 2200 of FIG. 22, whereinthe current sensor 2450 comprises a sense resistor that is seriallyconnected between the load side of the solid-state switch 2410 and theload hot 121. In some embodiments, the current sensor 2450 utilizes thesame sense resistor 2442 as the zero-crossing detection circuitry 2440,wherein the current sensor 2450 would have inputs connected to nodes N1and N2 to sample the sense voltage V_(Sense).

The sensors 2460 include one or more optional sensors that areconfigured to sense environmental conditions (e.g., chemical, gas,humidity, water, temperature, light, etc.) and generate sensor data thatis indicative of potentially hazardous environmental conditions. Thesensors 2460 are coupled to the switch controller 2470 by one or moredata acquisition and control lines 2460-1. By way of example, thesensors 2460 can include one or more of (i) a chemical sensitivedetector that is configured to detect the presence of hazardouschemicals, (ii) a gas sensitive detector that is configured to detectthe presence of hazardous gases, (iii) a temperature sensor that isconfigured to detect high temperatures indicative of, e.g., a fire; a(iv) a piezoelectric detector that is configured to detect largevibrations associated with, e.g., explosions, earthquakes, etc., (v) ahumidity sensor or water sensor that is configured to detect floods ordamp conditions, and other types of sensors that are configured todetect for the presence or occurrence of hazardous environmentalconditions that would warrant circuit interruption.

The switch controller 2470 operates in conjunction with thezero-crossing detection circuitry 2440, the current sensor 2450 and thesensors 2460 to perform functions such as detecting fault conditions(e.g., short-circuit faults, over-current faults, arc-faults,ground-faults, etc.), detecting hazardous environmental conditions(e.g., gas leaks, chemical spills, fire, floods, etc.), and to providetiming control for the opening and closing of the switches 2410 and 2420in response to detected fault conditions or hazardous environmentalconditions, to thereby avoid creating electrical arcs in the air-gapelectromagnetic switch 2420. The switch controller 2470 generates gatecontrol signals that are applied to the gate terminal (G) of thesolid-state switch 2410 to place the solid-state switch 2410 into aswitched-on or a switched-off state. In some embodiments, the switchcontroller 2470 generates a gate control signal to place the solid-stateswitch 2410 into a switched-off state in response to fault conditionssuch as short-circuit faults, over-current faults, over-voltageconditions, and other faults or hazards that are detected by the switchcontroller 2470 as a result of analyzing sensor data obtained from thecurrent sensor 2450 and/or the other sensors 2460.

The switch controller 2470 can be implemented using a processor that isconfigured to process sensor data and implement switch control timingprotocols as discussed herein for controlling the switches 2410 and2420. In addition, the switch controller 2470 can implement circuitryfor converting the sensor data into proper formats that are suitable forprocessing by the processor. In other embodiments, the switch control2470 implements hardware-based switch control circuitry (as in theexemplary embodiments discussed above) to enable hardware-based control,as opposed to software based control.

The switch controller 2470 can include an RF transceiver to wirelesslycommunicate with a remote node, device, system, etc., to support remotemonitoring and detection of fault conditions and to receive remotecommands for controlling the intelligent circuit breaker 2400. Theprocessor may comprise a central processing unit, a microprocessor, amicrocontroller, an application-specific integrated circuit (ASIC), afield programmable gate array (FPGA), and other types of processors, aswell as portions or combinations of such processors, which can performprocessing functions based on software, hardware, firmware, etc. Inother embodiments, the solid-state circuitry of the various components(e.g., 2430, 2440, and 2470) of the intelligent circuit breaker 2400 canbe implemented on a single die as a system-on-chip.

To prevent the generation of electrical arcs between the electricalcontacts of the electromagnetic switch 2420, the switch controller 2470is configured to place the solid-state switch 2410 into a switched-offstate before placing the air-gap electromagnetic switch 2420 into aswitched-open or switched-closed state. However, in the configuration ofFIG. 24, even when the solid-state switch 2410 is in a switched-offstate, and assuming the air-gap electromagnetic switch 2420 is in aswitched-closed state, the body diode 2410-1 of the solid-state switch2410 will allow negative current to conduct from the load 120 to the ACmains 110 when the AC power supply waveform of the AC mains 110 is in anegative half-cycle.

In this instance, if the air-gap electromagnetic switch 2420 is openedduring the negative half cycle of the AC power supply waveform, the flowof negative current would generate electrical arcs between theelectrical contacts of the air-gap electromagnetic switch 2420. Inaddition to generation of electrical arcs, it could be difficult or notpossible to open the air-gap electromagnetic switch 2420 due torelatively strong electro-magnetic forces that would be generated due toshort-circuit current conditions and the negative current flow at thegiven time.

To avoid creating such electrical arcs, and enable ease of opening theair-gap electromagnetic switch 2420, the switch controller 2470 isconfigured to place the solid-state switch 2410 in a switched-off statein response to detecting a fault or hazardous condition, and process thesensor data obtained from the zero-crossing detection circuitry 2440 todetermine a zero-crossing event of the AC voltage and/or current on theline side (e.g., line hot 111) of the intelligent circuit breaker 2400and associated transition direction of the zero-crossing event, and theopen the air-gap electromagnetic switch 2420 in response to the detectedzero-crossing event if the polarity of the AC voltage and/or current onthe line side is determined to be transitioning to a positive halfcycle.

On the other hand, when the switch controller 2470 determines, at agiven time, that the associated transition direction of thezero-crossing event is a negative transition where the polarity of theAC voltage and/or current on the line side is transitioning to anegative half cycle, the switch controller 2470 will not open theair-gap electromagnetic switch 2420, but rather defer opening theair-gap electromagnetic switch 2420 until the next instance of azero-crossing event with a positive transition as detected by thezero-crossing detection circuitry 2440. In this instance, the air-gapelectromagnetic switch 2420 would be opened during the half-cycle inwhich the solid-state switch 2410 is preventing all current flow (lessany leakage). This switch control protocol enables a significantdown-sizing of the size and strength requirements of theelectro-mechanical mechanism for opening the air-gap electromagneticswitch 2420.

The switch timing control implemented by the switch controller 2470 willnow be discussed in further detail with reference to FIGS. 25A, 25B and26. For example, FIG. 25A illustrates a power supply voltage waveformthat is input to a line side of the intelligent circuit breaker 2400 ofFIG. 24. In particular, FIG. 25A, illustrates an input voltage waveform2500 which represents a power supply voltage waveform of the AC mains110. The input voltage waveform 2500 comprises positive half cycles2502, negative half cycles 2504, and zero voltage crossings 2510 attimes T0, T1, T2, T3, and T4. When the solid-state switch 2410 is inswitched-on state and the air-gap electromagnetic switch 2420 is inswitched-closed state, the input voltage waveform 2500 is applied to theload hot line 121 of the load 120. When the switch controller 2470determines that power should be disconnected from the load 120, theswitch controller 2470 will generate a gate control signal that isapplied to the gate terminal G of the solid-state switch 2410 to placethe solid-state switch 2410 into a switched-off state.

FIG. 25B illustrates an output voltage waveform 2520 on a load side ofthe intelligent circuit breaker 2400 of FIG. 24 when the solid-stateswitch 2410 is in a switched-off state and the air-gap electromagneticswitch 2420 is in a switched-closed state. In this state, the body diode2410-1 of the solid-state switch 2410 is forward biased during thenegative half cycles 2504 of the input voltage waveform 2500, whichrectifies the input voltage waveform 2500 and results in the outputvoltage waveform 2520 shown in FIG. 25B wherein portions 2522 of theoutput voltage waveform 2520 which correspond to the positive halfcycles 2502 of the input waveform 2500 are at 0V, and wherein portions2524 of the output voltage waveform 2520 track the voltage of thenegative half cycles 2504 of the input waveform 2500. In this instance,negative current would flow from the load 120 to the AC mains 110 duringeach negative half cycle 2524 until the air-gap electromagnetic switch2420 was opened.

As noted above, after the solid-state switch 2410 is switched-off, theswitch controller 2470 will process the sensor data obtained from thezero-crossing detection circuitry 2440 to determine a zero-crossingevent of the AC voltage waveform (and/or an AC current waveform) on thehot line path of the intelligent circuit breaker 2400 and the transitiondirection of the zero-crossing event. The switch controller 2470 willgenerate a control signal to open the air-gap electromagnetic switch2420 in response to the detected zero-crossing event if the AC voltagewaveform is transitioning to a positive half-cycle. For instance, whileFIG. 25A shows zero-crossing events 2510 of the AC waveform 2500 attimes T0, T1, T2, T3 and T4, only the zero-crossing events 2510 at timesT0, T2 and T4 have a positive transition direction where the AC waveform2500 transitions to a positive half-cycle.

In this instance, the switch controller 2470 will generate a controlsignal to open the air-gap electromagnetic switch 2420 to fullydisconnect power to the load 120, in response to a zero-crossing eventat times T0, T2 or T4. In particular, as shown in FIG. 25A, in someembodiments, in response to detecting a positive transitioningzero-crossing event (e.g., at times T0 or T2), the switch controller2470 will wait for a short time delay T_(s) (e.g., about 10 μs) beforegenerating a switch control signal to open the air-gap electromagneticswitch 2420. This brief delay time T_(s) ensures that the AC waveform isslightly positive and that no current is flowing in the hot line path,thereby preventing possible electrical arc formation in the air-gapelectromagnetic switch 2420 and allowing the air-gap electromagneticswitch 2420 to easily open without jitter due small current flow.

On the other hand, assume that a fault condition occurs and thesolid-state switch 2410 is switched-off in the time period between T0and T1 in FIGS. 25A and 25B. In this example, the switch controller 2470would determine that a next zero-crossing event 2510 of the AC waveform2500 at time T1 is a negative transitioning zero-crossing event. In thisinstance, the switch controller 2470 would wait for the next positivetransitioning zero-crossing event 2510 at time T2 before generating acontrol signal (at a delayed time T_(s) after detecting thezero-crossing event at time T2) to open the air-gap electromagneticswitch 2420. Again, this ensures that AC waveform 2500 is slightlypositive and that no current is flowing in the hot line path, therebypreventing possible electrical arc formation in the air-gapelectromagnetic switch 2420 and allowing the air-gap electromagneticswitch 2420 to easily open without jitter due small current flow.

It is to be understood that the exemplary voltage waveforms 25A and 25Brepresent a load 120 having a power factor of about one (1) where it isassumed that AC voltage waveform and the current drawn by the load 120are in phase. In such instance, the zero voltage crossings are assumedto be zero current crossings. However, in instances where the load 120has a power factor that is less than 1 (e.g., capacitive or inductiveload), the voltage waveform and current drawn by the load 120 will beout of phase. In this regard, the zero-crossing detection circuitry 2440can include a current zero-crossing detector to determine zero currentcrossings, or positive transitioning zero current crossings, of acurrent waveform on the line side of the switches 2420 and 2410 toensure that no positive current is flowing in the line hot path beforeopening the air-gap electromagnetic switch 2420. For example, as notedabove, in some embodiments, the zero-crossing detection circuitry 2420implements the current zero-crossing detection circuit 2000 of FIG. 20.

FIG. 26 is a flow diagram of a switch control process which isimplemented by the switch controller 2470 of the intelligent circuitbreaker 2400 of FIG. 24, according to an embodiment of the disclosure.The switch control process of FIG. 26 represents a non-limitingexemplary embodiment for recovery of utility power or a manual,automatic, or remote activation control to activate the intelligentcircuit breaker 2400 (block 2600). In this example, it is assumed thatthe solid-state switch 2410 is in a switched-off state, and the air-gapelectromagnetic switch 2420 is in a switched-closed state.

The switch controller 2470 waits to detect a proper zero crossing (block2602) before closing the air-gap electromagnetic switch 2420 (block2604). While it is ideal to wait for a voltage and/or current zero crossevent prior to closing the air-gap electromagnetic switch 2420, one ofordinary skill in the art will understand that this is not a mandatorycondition for closure. The zero-crossing event can be a positivetransitioning zero-crossing event or a negative transitioningzero-crossing event. As noted above, in some embodiments, it ispreferable to close the air-gap electromagnetic switch 2420 at thezero-crossing of an upcoming half cycle in which the body diode (e.g.,diode 2410-1) of the solid-state switch (e.g., switch 2410) is notforward biased and conducting. For example, in the exemplary embodimentof FIG. 24, the body diode 2410-1 of the solid-state switch 2410 isreversed biased and non-conducting during positive half cycles of thesupply voltage waveform of the AC mains 110. In such an embodiment, itis ideal to place the air-gap electromagnetic switch into aswitched-closed state (block 2604) upon detecting a positivetransitioning (current or voltage) zero-crossing event.

In other embodiments, depending on the type of MOSFET that is used toimplement the solid-state switch 2410, it may be ideal to close theair-gap electromagnetic switch 2420 upon detecting a negativetransitioning (current or voltage) zero-crossing event. For example, inan exemplary embodiment where the solid-state switch 2410 in FIG. 24 isimplemented as a P-type enhancement MOSFET with a drain terminal coupled(line side) to the air-gap switch 2420 and a source terminal coupled(load side), the body diode of the P-type MOSFET would have its anodeconnected line side and its cathode disposed load side. In suchinstance, the body diode of the P-type solid-state switch would bereversed biased and non-conducting during negative half cycles of thesupply voltage waveform of the AC mains 110. As such, when the P-typesolid-state switch is in a switched-off state, it would be ideal toclose the air-gap electromagnetic switch 2420 upon detecting a negativetransitioning (current or voltage) zero-crossing event. The same wouldapply for a circuit configuration in which the N-type solid-state switch2410 as shown in FIG. 24 is reversed with the source terminal connectedline side and the drain terminal connected load side.

When the air-gap electromagnetic switch 2420 is closed, the switchcontroller 2470 will proceed to generate a gate control signal to placethe solid-state switch 2410 into a switched-on state (block 2606). Thesolid-state switch 2410 may be switched-on at any time after the air-gapelectromagnetic switch 2420 is closed. For example, the intelligentcircuit breaker 2400 may operate in a “stand-by” mode where the air-gapelectromagnetic switch 2420 is maintained in switched-closed state, andthe switch controller 2470 waits for the occurrence of some triggeringevent (e.g., remote command) to proceed with activating the solid-stateswitch 2410.

When both switches 2410 and 2420 are activated, the switch controller2470 will enter a waiting state for some event or command to interruptthe circuit connection between power and load (block 2608). During thewaiting period, the solid-state switch 2410 and the air-gapelectromagnetic switch 2420 will be maintained in an activated state(block 2610). The event can be the detection of a given fault conditionor hazardous condition as determined by the switch controller 2470processing sensor data received from the various sensors 2450 and 2460.The command can be a manual command or automated command to interruptthe circuit connection.

Upon detecting a fault or hazardous condition (affirmative determinationin block 2608) or in response to a manual or automated command to tripthe circuit breaker, the switch controller 2470 will generate a gatecontrol signal to place the solid-state switch 2410 into a switched-offstate (block 2612). The switch controller 2470 will then proceed toprocess data from the zero-crossing detection circuitry 2440 to detect atarget zero-crossing event (e.g., a positive transitioning zero-crossingevent) on the line hot path (block 2614), and in response to detectingthe target zero-crossing event (affirmative determination in block2614), the switch controller 2470 will generate a switch control signalto place the air-gap electromagnetic switch 2420 into a switched-openstate (block 2616).

The switch controller 2470 will enter a wait state (block 2618) to waitfor the fault event or hazardous condition to be cleared, and maintainthe solid-state and air-gap electromagnetic switches in a deactivatestate (block 2620). When the fault event or hazardous condition iscleared (affirmative determination in block 2618), or when the switchcontroller 2470 otherwise receives a manual or remote command indicatingto reconnect power to the load, the control process returns to block2600, wherein the switch controller 2470 proceeds to reactivate theair-gap and solid-state switches and, thereby reconnect the power supplyto the load. It is to be understood that while the process flow of FIG.26 does not explicitly include process steps for performingzero-crossing detection prior to opening and closing the solid-stateswitch 2410, one of ordinary skill in the art will recognize andappreciate that for certain applications, the switching on and off ofthe solid-state switch 2410 may be timed with either a voltage orcurrent zero-crossing event, as desired.

FIG. 27 schematically illustrates an intelligent circuit breakeraccording to another embodiment of the disclosure. In particular, FIG.27 schematically illustrates an intelligent circuit breaker 2700connected between an AC mains 110 and a load 120. The intelligentcircuit breaker 2700 is similar to the intelligent circuit breaker 2400of FIG. 24, except that the intelligent circuit breaker 2700 of FIG. 27implements a thermal electromechanical circuit breaker switch 2710 (inplace of the air-gap electromagnetic switch 2420 in FIG. 24), aninternal switch 2720, and a shunt resistor 2730. In some embodiments,the thermal electromechanical circuit breaker switch 2710 comprises aconventional circuit breaker architecture, such as discussed above inconjunction with FIG. 1A.

The internal switch 2720 and the shunt resistor 2730 are seriallyconnected between a node N3 and ground (neutral) 114, wherein the nodeN3 comprises a connection point between the thermal electromechanicalcircuit breaker switch 2710 and the solid-state switch 2410. In someembodiments, as shown in FIG. 27, the internal switch 2720 comprises asolid-state bidirectional switch comprising a first MOSFET switch 2721and a second MOSFET switch 2722 (e.g., N-channel MOSFET switches) whichare serially connected back-to-back with commonly connected sourceterminals and commonly connected gate terminals. The commonly connectedgate terminals of the first and second MOSFET switches 2721 and 2722 areconnected to a control output port of the switch controller 2470. Thefirst and second MOSFET switches 2721 and 2722 have intrinsic bodydiodes (not specifically shown in FIG. 27).

As in the exemplary embodiment of FIG. 24, the switch controller 2470operates in conjunction with the zero-crossing detection circuitry 2440,the current sensor 2450 and the other sensors 2460 to perform functionssuch as detecting fault conditions (e.g., short-circuit conditions,over-current conditions, over-voltage conditions, arc-faults,ground-faults, etc.), and detecting hazardous environmental conditions(e.g., gas leaks, chemical spills, fire, floods, etc.). The switchcontroller 2470 is configured to apply a control signal to the gateterminal (G) of the solid-state switch 2410 to control the activation(switched-on) and deactivation (switched-off) of the solid-state switch2410. In addition, the switch controller 2470 is configured to generatea control signal to control the activation and deactivation of theinternal switch 2720. The switch controller 2470 implements a timingcontrol protocol that is configured to control the timing of theactivation/deactivation of solid-state switch 2410 and the internalswitch 2720 under different operating conditions of the intelligentcircuit breaker 2700.

For instance, the switch controller 2470 generates a gate control signalto place the solid-state switch 2410 into a switched-off state inresponse to detected fault conditions such as short-circuit faults,over-current faults, over-voltage conditions, and other faults orhazards which are detected by the switch controller 2470 as a result ofanalyzing sensor data obtained from the current sensor 2450 and/or theother sensors 2460. In addition, after the solid-state switch 2410 isswitched-off, the switch controller 2470 generates a control signal toactivate the internal switch 2720 and thereby generate an internalshort-circuit between the node N3 and ground 114. The internalshort-circuit between the node N3 and ground 114 causes over-current toflow through the thermal electromechanical circuit breaker switch 2710and thereby trip the thermal electromechanical circuit breaker switch2710 and create an air-gap in the electrical path between the line hot110 and the load hot 121.

In other words, in this embodiment, the switch controller 2470 does notgenerate a control signal which is applied directly to the thermalelectromechanical circuit breaker switch 2710 to trip the thermalelectromechanical circuit breaker switch 2710. Instead, the switchcontroller 2470 applies a gate control signal to the commonly connectedgate terminals of the first and second MOSFET switches 2721 and 2722 toturn on the first and second MOSFET switches 2721 and 2722. This createsan internal short-circuit between the node N3 and ground 114 withcurrent flowing through the shunt resistor 2730, which causes thethermal electromechanical circuit breaker switch 2710 to trip. Theinternal switch 2720 is deactivated (e.g., the first and second MOSFETswitches 2721 and 2722 are switched-off) at some point in time after thethermal electromechanical circuit breaker switch 2710 is tripped andbefore the intelligent circuit breaker 2700 is reset for normaloperation.

In some embodiments, the resistance of the shunt resistor 2730 isselected so that the short-circuit current flow from the node N3 toground 114 is in range of about 2× to 3× the current rating of thethermal electromechanical circuit breaker switch 2710. For example, ifthe thermal electromechanical circuit breaker switch 2710 has a currentrating of 20 amperes, the resistance of the shunt resistor 2730 isselected so that a maximum of approximately 40 to 60 amperes of currentflows through the thermal electromechanical circuit breaker switch 2710and through the short-circuit branch between the node N3 and ground 114to cause the thermal electromechanical circuit breaker switch 2710 totrip and generate an air-gap in the electrical path between the line hot110 and the load hot 121.

In some embodiments, the switch controller 2470 is configured to utilizezero-crossing detection signals output from the zero-crossing detectioncircuit 2440 to determine when to activate the internal switch 2720 andthereby create the short-circuit between the node N3 and ground 114,which causes the thermal electromechanical circuit breaker switch 2710to trip. For example, similar to the exemplary embodiments discussedabove in connection with FIGS. 24-26, when the zero-crossing detectioncircuit 2440 is configured to detect a direction of polaritytransitioning between opposing half cycles of the AC voltage waveform orthe AC current waveform on the line side of the thermalelectromechanical circuit breaker switch 2710, the switch controller2470 is configured to activate the internal switch 2720 at a time whenthe polarity transitioning causes the body diode 2410-1 of thedeactivated solid-state switch 2410 to be reversed-biased.

In the exemplary embodiment of FIG. 27, the body diode 2410-1 of thesolid-state switch 2410 is reversed-biased during positive half cyclesof the AC voltage waveform or the AC current waveform on the line sideof the thermal electromechanical circuit breaker switch 2710. However,the body diode 2410-1 of the solid-state switch 2410 will beforward-biased and allow negative current to conduct from the load 120to the AC mains 110 through the thermal electromechanical circuitbreaker switch 2710 when, e.g., the AC power supply waveform of the ACmains 110 is in a negative half-cycle.

In this instance, if the internal switch 2720 is activated during thenegative half cycle of the AC power supply waveform, the current flowthrough the thermal electromechanical circuit breaker switch 2710 wouldbe a combination of (i) the negative current flow from the load 120 tothe AC mains 110 and (ii) the current flow that is generated in theshort-circuit path from the ground 114 to the node N3, thereby providingan increased current flow through the thermal electromechanical circuitbreaker switch 2710 to trip the thermal electromechanical circuitbreaker switch 2710. This can result in the generation of high-energyelectrical arcs between the electrical contacts of the thermalelectromechanical circuit breaker switch 2710 when tripped.

In contrast, by ensuring the that the internal switch 2720 is activatedat a time when the polarity transitioning causes the body diode 2410-1of the solid-state switch 2410 to be reversed-biased, the amount ofcurrent flow through the thermal electromechanical circuit breakerswitch 2710 is at least initially limited to the current that isgenerated in the short-circuit path between the node N3 and ground 114based on the resistance value of the shunt resistor 2730. In thisinstance, the amount of short-circuit current that is generated to tripthe thermal electromechanical circuit breaker switch 2710 can becontrolled/limited by the shunt resistor 2730 and thus limit the amountof electrical arcing that is generated between the electrical contactsof the thermal electromechanical circuit breaker switch 2710 whentripped. In other words, by timing the activation of the internal switch2720 to a time when the body diode 2410-1 of the deactivated solid-stateswitch 2140 is reversed-biased, the intelligent circuit breaker 2700avoids using the actual short-circuit load current to trip theconventional thermal electromechanical circuit breaker switch 2710, andinstead, utilizes the limited/controlled internal short-circuit current(which is generated by activation of the internal switch 2720) to tripthe circuit breaker switch 2710.

In other embodiments, an intelligent circuit breaker is designed toinclude one or more visual indicators that allow an individual todetermine an operational state of the intelligent circuit breaker. Forexample, FIGS. 28A, 28B, 28C, 28D and 28E are perspective and schematicviews of an intelligent circuit breaker 2800 which comprises multiplevisual indictors that are configured to indicate operational states ofthe intelligent circuit breaker 2800. In particular, FIGS. 28A and 28Bare perspective views of the intelligent circuit breaker 2800 whichcomprises a circuit breaker housing 2810 (or enclosure), a manual rockerswitch 2820, a first visual indicator 2830, and a second visualindicator 2840. The manual rocker switch 2820 comprises an OFF positionand an ON position which allows an individual to manually trip and resetthe intelligent circuit breaker 2800. As explained in further detailbelow, the first and second visual indictors 2830 and 2840 areconfigured to provide a visual status of the operational state(s) of theintelligent circuit breaker 2800.

FIGS. 28C, 28D, and 28E schematically illustrate various componentswithin the circuit breaker housing 2810 of the intelligent circuitbreaker 2800. For example, as shown in FIGS. 28C-28E, the componentsinclude an actuator mechanism 2850, a solenoid 2860, and an air-gapswitch 2870. The air-gap switch 2870 comprises a first fixed contact2871 and a second movable contact 2872 which is connected to theactuator mechanism 2850. The manual rocker switch 2820 and solenoid 2860are connected to the actuator mechanism 2850. The actuator mechanism2850 is configured to control the position of the movable contact 2872in relation to the fixed contact 2871 in response to (i) a manualactuation of the rocker switch 2820 and (ii) a magnetic actuation of thesolenoid 2860. In this configuration, the solenoid 2850 is configured tobe magnetically actuated in response to high over-currents, whereinmagnetic actuation of the solenoid 2860 results in a mechanicalactuation of the actuator mechanism 2850 to cause the movable contact2872 to separate from the fixed contact 2871 of the air-gap switch 2870.For ease of illustration and explanation, FIGS. 28C, 28D, and 28E do notillustrate the circuit board(s) and associated solid-state circuitrywhich is used to implement the various intelligent functionalities ofthe intelligent circuit breaker 2800, as discussed above.

FIGS. 28C, 28D, and 28E illustrate different operational states of theintelligent circuit breaker 2800. In particular, FIG. 28C illustrates anoperational state in which the air-gap switch 2870 is “Open” with thefirst and second contacts 2871 and 2872 separated to form an air-gap2873. In FIG. 28C, the manual rocker switch 2820 is in an “OFF”position. In this instance, the air-gap switch 2870 is manually openedby moving the rocker switch 2820 from the ON position to the OFFposition, wherein the actuation of the rocker switch 2820 in thisinstance causes the actuator mechanism 2850 to move the movable contact2872 away from the fixed contact 2871.

Next, FIG. 28D illustrates an operational state in which the air-gapswitch 2870 is “Closed” with the first and second contacts 2871 and 2872making electrical contact with the air-gap 2873 closed. In FIG. 28D, themanual rocker switch 2820 is in an “ON” position, and the solenoid 2860is in a closed position. In this instance, the air-gap switch 2870 ismanually closed by moving the rocker switch 2820 from the OFF positionto the ON position, wherein the actuation of the rocker switch 2820 inthis instance causes the actuator mechanism 2850 to move the movablecontact 2872 against the fixed contact 2871. FIG. 28D illustrates anormal operating state of the intelligent circuit breaker 2800.

Next, FIG. 28E illustrates an operational state in which the air-gapswitch 2870 is “Open” with the first and second contacts 2871 and 2872separated to form an air-gap 2873. In FIG. 28E, it is assumed that themanual rocker switch 2820 is in an “ON” position, and that theintelligent circuit breaker 2800 is in a “tripped” state as a result ofthe magnetic actuation of the solenoid 2860 (e.g., solenoid 2860 in anopen position) causing the actuator mechanism 2850 to move the movablecontact 2872 away from the fixed contact 2871 and thereby open theair-gap switch 2870 to form the air-gap 2873. In this instance, theintelligent circuit breaker 2800 is tripped electromechanically, and theintelligent circuit breaker 2800 is reset by moving the manual rockerswitch 2820 from the ON position, to the OFF position, and then back tothe ON position.

As collectively shown in FIGS. 28A-28E, the first visual indicator 2830comprises a window 2832 (e.g., glass or plastic window) that is formedas part of the circuit breaker housing 2810 and a status LED 2834 whichis disposed within the circuit breaker housing 2810 behind the window2832. The status LED 2834 is illuminated to indicate a status (e.g., On,Off, Standby, wireless status, provisioning, etc.) of the intelligentcircuit breaker 2800. The status LED 2834 can emit different colors(e.g., red, green, etc.) and/or have different illumination patterns(e.g., continuous, blinking, etc.) to represent different operationalstates. In some embodiments, the status LED 2834 is only operationalwhen utility power is present.

FIG. 28A illustrates an exemplary embodiment in which the status LED2834 of the first visual indicator 2830 is illuminated with a firstcolor (e.g., red) when the intelligent circuit breaker 2800 is in a“tripped” state in which the manual rocker switch 2820 is in an ONposition but the air-gap switch is in an Open state. In otherembodiments, the status LED 2834 of the first visual indicator 2830 canbe illuminated with another color (e.g., green) when the intelligentcircuit breaker 2800 is operating normally (e.g., non-tripped state)with the manual rocker switch 2820 in the ON position.

FIG. 28B illustrates an exemplary embodiment in which the status LED2834 of the first visual indicator 2830 is not illuminated when theintelligent circuit breaker 2800 is in an Off state (e.g., not connectedto utility power, or connected to utility power but the manual rockerswitch 2820 is in the OFF position). In this instance, when the statusLED 2834 is not illuminated, the viewing window 2832 can have atranslucent colored coating with a color that is the same or similar tothe color of the circuit breaker housing 2810.

Furthermore, as collectively shown in FIGS. 28A-28E, the second visualindicator 2840 comprises a window 2842 (e.g., glass or plastic window)that is formed as part of the circuit breaker housing 2810, and a firstcolored element 2844 (or more generally, a first indicator element), anda second colored element 2846 (or more generally, a second indicatorelement) which are disposed within the circuit breaker housing 2810 andselectively positioned behind the window 2832 to show differentoperational states of the intelligent circuit breaker. Morespecifically, in some embodiments, the second visual indicator 2840 isconfigured to provide a status of the air-gap switch 2870 (Open orClosed).

For example, the first and second colored elements 2844 and 2846comprise colored pieces of plastic that are bonded to portions of theactuator mechanism 2850 or otherwise comprise painted surfaces onportion of the actuator mechanism 2850. The first and second coloredelements 2844 and 2846 are selectively disposed behind the viewingwindow 2842 to allow an individual to view the color and therebydetermine the status of the air-gap switch 2870 based on the color seenthrough the viewing window 2842. For example, the second colored element2846 can be a red color which indicates that the air-gap is in an “Open”state, while the first colored element 2844 can be a non-red color(e.g., black) which indicates that the air-gap is in a “Closed” state.In other embodiments, the first and second indicator elements 2844 and2846 can implement other means of indicating the status of the air-gapswitch 2870, such as words, patterns, etc., in addition to and/or inplace of the different colors.

For example, FIGS. 28C and 28E schematically illustrate a state in whichthe air-gap switch 2870 is in an “Open” state by virtue of the manualactuation of the rocker switch 2820 to the OFF position (FIG. 28C) or byvirtue of the magnetic actuation of the solenoid 2860 which causes theair-gap switch 2870 to open and trip the intelligent circuit breaker2800. In this state, the second colored element 2846 is positionedbehind the viewing window 2842 by the movement of actuator mechanism2850 to open the air-gap switch 2870, while the first colored element2844 is positioned away from the viewing window 2842.

On the other hand, FIG. 28D schematically illustrates a state in whichthe air-gap switch 2870 is in a “Closed” state by virtue of the manualactuation of the rocker switch 2820 which causes the air-gap switch 2870to close. In this state, the first colored element 2844 is positionedbehind the viewing window 2842 by the movement of actuator mechanism2850 to close the air-gap switch 2870, while the second colored element2846 is positioned away from the viewing window 2842. In this regard,the second the second visual indicator 2840 is fully-functional evenwhen utility power is absent, and provides an “air-gap open” indicatorfor safety.

FIG. 29 schematically illustrates an intelligent circuit breaker 2900according to another embodiment of the disclosure. The intelligentcircuit breaker 2900 is similar to the intelligent circuit breaker 2800of FIGS. 28A-28E, except that the intelligent circuit breaker 2900comprises a secondary internal sensing switch 2910 (e.g.,electromechanical detector) which is coupled to the manual rocker switch2820. The sensing switch 2910 is configured to detect an anticipatedmanual state change of the rocker switch 2820 from, e.g., an ON position(air-gap switch 2870 closed) to an OFF (air-gap switch 2870 open). Thesensing switch 2910 triggers the electronics (e.g., solid-state switchcontrol circuitry) of the intelligent circuit breaker 2900 to activateor deactivate the solid-state switch (e.g., bidirectional solid-stateswitch) before the air-gap switch 2870 finishes its motion of opening orclosing, which takes a moment of time, e.g., an order of magnitude ortwo longer than it takes to open/close the solid-state switch. Theinternal sensing switch 2910 ensures that, e.g., air-gap switch 2870 isnot opened under high load current, or that the air-gap switch 2870 isclosed before the solid-state switch is activated.

While exemplary embodiments have been discussed above in the context ofintelligent circuit breakers for use with AC supply power, it is to beappreciated that the intelligent circuit breakers can be configured foruse with DC supply power. There are various systems (e.g.telecommunications systems) that operate on DC supply power instead ofAC supply power. In these systems, the AC power delivered/provided by autility company can be converted on site to DC supply power (using anAC-to-DC power conversion system), wherein the DC supply power is thenfed to one or more DC distribution panels with DC circuit breakers thatfeed downstream branch circuits and loads.

The exemplary intelligent circuit breakers as discussed herein can beconfigured to operate in either an “AC protection mode” or a “DCprotection mode” depending on whether AC power or DC power is applied tothe line input terminal of the intelligent circuit breaker. For example,upon power-up of the intelligent circuit breaker, the solid-statecircuitry (e.g., sensors, processor, etc.) of the intelligent circuitbreaker can be configured to detect whether AC power or DC power isapplied to the line input terminal of the intelligent circuit breaker,and then automatically configure the intelligent circuit breaker tooperate in either the AC protection mode or the DC protection mode,depending on the detected input power.

More specifically, in some embodiments, when power is initially appliedto the line input terminal of the intelligent circuit breaker, a voltagesensor or zero-crossing detector coupled to the line side of theswitches of the intelligent breaker can monitor the voltage waveform andsend sensor data to the processor. The processor of the intelligentcircuit breaker can analyze the sensor data to determine whether theinput power is AC or DC. For example, the processor can determine thatDC power is applied to the line input terminal when the voltage sensordata indicates that a magnitude of the input voltage remains at aconstant level for a predetermined period of time, and/or when thezero-crossing detection circuitry does not output a zero-crossing eventsignal within the predetermined period of time. On the other hand, theprocessor can determine that AC power is applied to the line inputterminal when the voltage sensor data indicates that the magnitude ofthe input voltage is varying and/or when the zero-crossing detectioncircuitry outputs multiple zero-crossing event signals within thepredetermined period of time.

In some embodiments, the processor (e.g., microprocessor, controllers,etc.) of the intelligent circuit breaker can be configured to processdifferent embedded software programs (e.g., different state machines)for the different protection modes. The embedded software programs forthe different protection modes comprise different program instructionsand utilize different pre-defined parameters or register values toenable the processor to make intelligent control decisions in responseto detecting and responding to fault conditions (e.g., short-circuit,over-current, over-voltage, etc.) depending on the detected supply power(AC or DC power). For example, different threshold values and timingconsiderations for identifying and protecting against over-current orover-voltage conditions will vary depending on whether the intelligentcircuit breaker is operating in a DC protection mode of an AC protectionmode.

In addition, the switch control protocols for controlling the activationand deactivation of the switches (e.g., solid-state bidirectionalswitches) of the intelligent circuit breaker will vary depending onwhether the intelligent circuit breaker is operating in a DC or an ACprotection mode. For example, in a DC protection mode, thegate-to-source voltage of both MOSFET devices of a solid-statebidirectional switch is controlled so that both MOSFET devices areswitched-on during normal operation, and both are switched-off inresponse to detection of fault condition. Moreover, to conserve power,some hardware circuitry of the intelligent circuit breaker can bedisabled depending on the whether the intelligent circuit breaker isoperating in a DC or AC protection mode. For example, a zero-crossingdetection circuit of the intelligent circuit breaker can be disabledwhen the intelligent circuit breaker is operating in in a DC protectionmode. In addition, in a DC protection mode, an AC-to-DC converter of theintelligent circuit breaker can be disabled, and a DC-to-DC converter ofthe intelligent circuit breaker can be selectively enabled to convertthe DC supply voltage (applied to the line input terminal of theintelligent breaker) to a lower DC voltage to power the solid-statecircuitry of the intelligent circuit breaker.

The exemplary embodiments of intelligent circuit breakers as discussedherein and illustrated through the drawings comprise various features,functions, components, etc., that can be utilized to implement differenttypes of intelligent circuit breakers for different applications. It isto be understood that an intelligent circuit breaker illustrated in onefigure can incorporate or more additional features illustrated in one ormore other figures to implement another architecture of an intelligentcircuit breaker. For example, all exemplary embodiments of intelligentcircuit breakers as illustrated through the figures can be configured toinclude arc-fault and/or ground-fault sensing and protectioncapabilities.

In this regard, although exemplary embodiments have been describedherein with reference to the accompanying figures, it is to beunderstood that the current disclosure is not limited to those preciseembodiments, and that various other changes and modifications may bemade therein by one skilled in the art without departing from the scopeof the appended claims.

We claim:
 1. A circuit breaker, comprising: a circuit breaker housing;an air-gap switch disposed within the circuit breaker housing, theair-gap switch comprising a first contact and a second contact disposedin an electrical path between a line input terminal and a load outputterminal of the circuit breaker; an actuator mechanism disposed withinthe circuit breaker housing, wherein the air-gap switch is coupled tothe actuator mechanism, and wherein the actuator mechanism isoperatively configured to (i) mechanically force the first and secondcontacts apart to place the air-gap switch into an open state and createan air-gap in the electrical path, and (ii) mechanically force the firstand second contacts together to place the air-gap switch into a closedstate; and a first visual indicator configured to provide an indicationof a state of the air-gap switch, wherein the first visual indicatorcomprises (i) a first window that is formed as part of the circuitbreaker housing, (ii) a first indicator element coupled to the actuatormechanism and (iii) a second indicator element coupled to the actuatormechanism; wherein the actuator mechanism is configured to move thefirst indicator element into position behind the first window as theactuator mechanism places the air-gap switch into the open state, suchthat the first indicator element is viewable through the first window toprovide an indication of the open state of the air-gap switch; andwherein the actuator mechanism is configured to move the secondindicator element into position behind the first window as the actuatormechanism places the air-gap switch into the closed state, such that thesecond indicator element is viewable through the first window to providean indication of the closed state of the air-gap switch.
 2. The circuitbreaker of claim 1, wherein the first indicator element comprises acolored element having a first color, and wherein the second indicatorelement comprises a colored element having a second color, which isdifferent from the first color.
 3. The circuit breaker of claim 1,further comprising a second visual indicator configured to provide anindication of an operational state of the circuit breaker, wherein thesecond visual indicator comprises (i) a second window that is formed aspart of the circuit breaker housing, and (ii) at least onelight-emitting element disposed within the circuit breaker housingbehind the second window.
 4. The circuit breaker of claim 3, wherein theat least one light-emitting element comprises a light-emitting diode. 5.The circuit breaker of claim 3, wherein the at least one light-emittingelement is configured to emit light of a first color which is viewablethrough the second window to provide an indication of a non-trippedoperating state of the circuit breaker.
 6. The circuit breaker of claim5, wherein the at least one light-emitting element is configured to emitlight of a second color which is viewable through the second window toprovide an indication of a tripped state of the circuit breaker.
 7. Thecircuit breaker of claim of claim 3, wherein the at least onelight-emitting element is deactivated and emits no light to provide anindication of an off state of the circuit breaker.
 8. The circuitbreaker of claim 1, further comprising a manual control switchmechanically coupled to the actuator mechanism, wherein the manualcontrol switch is configured to toggle between a first position and asecond position, wherein toggling the manual control switch into thefirst position causes the actuator mechanism to place the air-gap switchinto the open state.
 9. The circuit breaker of claim 1, furthercomprising an electromechanical actuator coupled to the actuatormechanism, wherein actuation of the electromechanical actuator causesthe actuator mechanism to place the air-gap switch into the open stateand trip the circuit breaker.
 10. The circuit breaker of claim 9,wherein the electromechanical actuator comprises a solenoid.
 11. Acircuit breaker, comprising: a solid-state switch and an air-gap switchconnected in series in an electrical path between a line input terminaland a load output terminal of the circuit breaker, wherein the air-gapswitch comprises a first contact and a second contact; an actuatormechanism operatively configured to (i) mechanically force the first andsecond contacts apart to place the air-gap switch into an open state andcreate an air-gap in the electrical path, and (ii) mechanically forcethe first and second contacts together to place the air-gap switch intoa closed state; a manual control switch operatively coupled to theactuator mechanism, wherein the manual control switch is configured totoggle between a first position and a second position, wherein togglingthe manual control switch into the first position causes the actuatormechanism to place the air-gap switch into the open state; anelectromechanical actuator operatively coupled to the actuatormechanism, wherein actuation of the electromechanical actuator causesthe actuator mechanism to place the air-gap switch into the open state;control circuitry configured to control operation of the solid-stateswitch and the electromechanical actuator, wherein the control circuitryis configured to generate (i) a first control signal that is configuredto place the solid-state switch into one of a switched-on state and aswitched-off state and (ii) a second control signal that is configuredto control actuation of the electromechanical actuator; and a sensorswitch operatively coupled to the manual control switch and electricallyconnected to the control circuitry, wherein the sensor switch isconfigured to (i) detect a toggling of the manual control switch fromthe second position to the first position which causes the actuatormechanism to place the air-gap switch into the open state and (ii) inresponse to detecting the toggling of the manual control switch from thesecond position to the first position, output a third control signal tothe control circuitry; wherein in response to the third control signal,the control circuitry is configured to generate the first control signalto place the solid-state switch into the switched-off state before theair-gap switch is placed into the open state to create the air-gap inthe electrical path.
 12. The circuit breaker of claim 11, furthercomprising: a current sensor configured to sense a current flowing inthe electrical path between the line input terminal and the load outputterminal, and detect a fault condition based on the sensed current flow;wherein in response to detecting a fault condition by the currentsensor, the control circuitry is configured to generate the first andsecond control signals to (i) place the solid-state switch into aswitched-off state and (ii) actuate the electromechanical actuator tocause the actuation mechanism to place the air-gap switch into the openstate after the solid-state switch is placed into the switched-offstate.
 13. The circuit breaker of claim 11, wherein theelectromechanical actuator comprises a solenoid.
 14. The circuit breakerof claim 11, further comprising: a first visual indicator configured toprovide an indication of the state of the air-gap switch, wherein thefirst visual indicator comprises (i) a first window that is formed aspart of a circuit breaker housing of the circuit breaker, (ii) a firstindicator element coupled to the actuator mechanism and (iii) a secondindicator element coupled to the actuator mechanism; wherein theactuator mechanism is configured to move the first indicator elementinto position behind the first window as the actuator mechanism placesthe air-gap switch into the open state, such that the first indicatorelement is viewable through the first window to provide an indication ofthe open state of the air-gap switch; and wherein the actuator mechanismis configured to move the second indicator element into position behindthe first window as the actuator mechanism places the air-gap switchinto the closed state, such that the second indicator element isviewable through the first window to provide an indication of the closedstate of the air-gap switch.
 15. The circuit breaker of claim 14,wherein the first indicator element comprises a colored element having afirst color, and wherein the second indicator element comprises acolored element having a second color, which is different from the firstcolor.
 16. The circuit breaker of claim 11, further comprising a secondvisual indicator configured to provide an indication of an operationalstate of the circuit breaker, wherein the second visual indicatorcomprises (i) a second window that is formed as part of the circuitbreaker housing, and (ii) at least one light-emitting element disposedwithin the circuit breaker housing behind the second window.
 17. Thecircuit breaker of claim 16, wherein the at least one light-emittingelement comprises a light-emitting diode.
 18. The circuit breaker ofclaim 16, wherein the at least one light-emitting element is configuredto: emit light of a first color which is viewable through the secondwindow to provide an indication of a non-tripped operating state of thecircuit breaker; emit light of a second color which is viewable throughthe second window to provide an indication of a tripped state of thecircuit breaker; and emit no light to provide an indication of an offstate of the circuit breaker.
 19. A circuit breaker comprising: acircuit breaker housing; an air-gap switch disposed within the circuitbreaker housing; and a first visual indicator configured to provide anindication of an open state and a closed state of the air-gap switch,wherein the first visual indicator comprises (i) a first window that isformed as part of the circuit breaker housing, (ii) a first indicatorelement disposed within the circuit breaker housing, and (iii) a secondindicator element disposed within the circuit breaker housing; whereinthe first indicator element is configured to move into position behindthe first window as the air-gap switch is placed into the open state,such that the first indicator element is viewable through the firstwindow to provide an indication of the open state of the air-gap switch;and wherein the second indicator element is configured to move intoposition behind the first window as the air-gap switch is placed intothe closed state, such that the second indicator element is viewablethrough the first window to provide an indication of the closed state ofthe air-gap switch.
 20. The circuit breaker of claim 19, furthercomprising: a second visual indicator configured to provide anindication of an operational state of the circuit breaker, wherein thesecond visual indicator comprises (i) a second window that is formed aspart of the circuit breaker housing, and (ii) at least onelight-emitting element disposed within the circuit breaker housingbehind the second window; wherein the at least one light-emittingelement is configured to emit light of at least one color through thesecond window to provide an indication of an operational state of thecircuit breaker corresponding to the at least one color.